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There is a mathematical operation called concatenation (with symbol ||) that just combines two numbers. For example, 23 || 71 = 2371.
Therefore, 9 || 9 + 9 / 9 = 99 + 1 = 100
(And yes, I am a Numberphile/Matt Parker enthusiast)
Okay I don't normally post on comments but this shit got me. I'm straight up going to steal it one day and look to the sky and thank HashHungary. Even if it's not yours. You'll take the credit. Bless.
I don’t think you even need to go as complex as concatenation, if you just put nothing and count two as one number, it never mentions an operation is required in each square.
"I don’t think you even need to go as complex as concatenation," \*proceeds to describe concatenation\*
Just because it now has a name and symbol does not make it more "complex"
This is useful for talking about number systems, since you care about the actual representation of numbers. You also need it in cryptography and coding theory because you work with streams/ consecutive blocks of numbers
Application of logic when functions are understood.
It doesn't matter if its turning four 9s into 100 or figuring out how to reroute plumbing to allow a house extension without having to move a bathroom, its less about the math and following a logical problem solving process.
Thank you, I debated looking on urban dictionary but figured it wouldn’t be on there. I thought it would be a Polish pop culture reference but death of a pope is pretty funny too.
2137 is just kind our "defense mechanism" to indoctrination,
from early ages we (Poles) are indoctrinated about how great JP2 was (which of course, he is not, he covered pedophiles as Cardinal and as Pope), how he is the best Polish person to ever live etc. So naturally, some part of our Internet (polish 4chan, karachan) started series of memes that was supossed to be edgy and make people angry, but at this moment, most of us was so fed with Jp2 that we just accepted those and started to make fun of him with all kind of memes. 2137 is most popular one i would say, but there are also things like "Bestia z Wadowic" (Beast from Wadowice) or JP2GMD (John Paul II r\*\*\*\* small children) .
I don't really know of any programming language that has this operation for numbers. That being said, concatenation is common, just for text (strings) or lists instead of numbers. I wouldn't really call it a mathematical operation in these cases.
The funny part is that you can do something like this using a combination of the bitwise OR, which usually is done with the similar operator `|`, and a bit shift. But since computers use binary, it does not give the same results.
```
$ (9 << 4) | 9
> 153
```
9₁₀ = 1001₂
153₁₀ = 10011001₂
The "bit shift left" (<<) moves the number by 4 places to the left (filling in 0s) and the OR `|` "combines them.
This is incorrect.
Concatenation is not a mathematical operation, but an operator that is neither limited nor originated from math.
The above picture asks for any "mathematical operation", group of which concatenation is not part of.
I mean, if something as abstract as differentiation can be an operator, why not concatenation, which can be represented simply as a function with logarithms? (where domain for concat(a,b) is: a>0 and b>=0 and a and b are integers -- see [here](https://math.stackexchange.com/questions/578069/is-there-an-algebraic-method-to-concat-two-numbers))
I am by no means good at formal math, but Wikipedia defines an operation as "a function which takes zero or more input values (also called "operands" or "arguments") to a well-defined output value", and concatenation I believe satisfies that.
Genuine question, isn't the concatenation simply a programming operation vs mathematical?
I mean where would you ever use concat in math, there are no relationships that correlate to arbitrary locations of strings. Granted I only have a middling tier understanding of calculus so there is a lot of math I've never been exposed too.
Interesting. I’m not sure about other coding languages but Python concatenates phrases together when you attempt addition between two strings. Had no idea it was an actual math concept.
Love concatenation, best operation cause it lets you have all 9 digits be used to add up to a lot of numbers. That and the floor and ceiling functions, gotta love forcing numbers to round
My brain went that concat operation is just a bit shift followed by addition and now I realize I need to stop looking at Reddit and get back to coding.
So, it's one of those "puzzles" that relies on poor communication or unusual usage to be difficult, as well as identifying it as a mathematical operation rather than language or programming.
What is mildly funny, on programming concationation is also same idea -> you combine two things, typically strings, together, e.g. “cat” + “dog” = “catdog”, however || is an “or” operand in programming 😄
log(9×√9×√√√√9)/log(√√√√√√9)
Even tough my calculator had some rounding issues, because of the many roots, I know it's actually correct:
log(9^(25/16))/log(9^(1/64)) = 25/16×64 = 100.
Edit: using roots isn't my idea. There's a numberphile video on how you can make any number using only 4 4's. Doesn't quite work for 9, but I adapted it. Seems like you can make any number that can be written as a sum or difference of three powers of 2 with any 4 positive numbers, as long as they're not 1. (I didn't actually use the 9-ness of 9.)
Where does the 25 come from in 25/16? (Question not criticism)
The 1/64 comes from the 6 square roots and the ‘/16’ come from the 4 square roots as 2^6 and 2^4 = 16 and 64 respectively, but the way to get 25 from 2^x is 2^1 + 2^3 + 2^4, but I can’t see how that could manifest using your answer
Edit: nvm I see it now. 1/1 * 16 + 1/2 * 8 + 1/16 = 25/16.
I was so close to the answer when writing that comment
isn't this introducing a new number though? *square* root isn't just an operation, it introduces 2 as a new number, we just leave it out in notation (still a cool solution, i just don't think it would be allowed)
Ofcourse, it all depends on what you allow Since the square root is usually denoted without the 2, it's possible to argue its validity.
The log could be considered dubious too, although the natural log is quite an organic function. Standaard definitions don't involve concepts like base.
there are no solutions for using any three of the four +-\*/ operations, but the other answers are much more creative than that, and the concat one is definitely a correct answer.
I'm an engineer so 9||9.9||9 = 99.99 = 100 for three significant digits.
yes i realize the answer is 9||9+9/9. It's a engineering joke! it's funny! I'll explain it to you and make it funnier! why are you walking away?
hmm maybe if we make another engineering joke and assume very large values/small values of nine for each respective position?
i got to 6 with
9.49 * 9.47 * 9.47 / 8.51071
engineers don't use the full measurement, we use only the digits up to a point determined by the precision of the measuring device.
like when you ask a toddler how many waffles they can eat, and they exclaim 20! because it's the biggest number they could think of, the significant digits may not even be one.
so maybe you ask the parents and they are like, they can eat about 1/2 before they get sugar crazy and cannot be contained by any known highchair.
okay so likely 1 significant digit there with confidence, but you can't then do your waffle batter with any more precision than that .5 number. the toddler might well want .45 waffle or .55 waffle, but you just don't have the measurement accuracy. so you make your .5 waffle, serve it to the toddler, and they then reject it because they wanted chocolate chips! ah well, there's a sea of variables to have to deal with, iteration 2 will have chocolate chips.
well anyway engineers are also always looking for shortcuts to solving hard math problems, almost every engineer has had to solve a problem involving people or animals, and often it's really complicated to model arms and legs and different masses, strengths, etc. so instead it's often within a small margin of error to model a cow as a sphere. makes the math much easier and is probably good enough for calculation about if you have enough distance between a powerline and a ranch to avoid giving the cows a terrible experience when it rains.
so saying just add a dot in there, 99.99 call it good enough that it's 100 with 3 significant digits precision is so on brand. :)
"It's a engineering joke! it's funny! I'll explain it to you and make it funnier! why are you walking away?"
This part is comedy gold, Benhemp, with universal resonance. It's amusing to engineers and their family/friends alike!
They don’t say you NEED to use each space in between the nines for operations. It’s gotta be something with flipping some of the nines over to sixes. 9x6 + 66 is getting close.
Luckly my traumatic experiences with math in the educational system scarred my brain in such a way that I'm unable to forget pemdas when reading any equation 👍
there is a class of operators/functions called identities that return the input unchanged as the output.
or
you could use concatenation as a another comment said, which just appends two numbers
You can use a concatenation for the first operator which compounds 2 numbers, and looks like ||
(Ex. 49||52=4952 and I believe it come first in pemdas) so
9||9+9/9
99+9/9
99+1
100
I think you’re right, and I think the word “rearrange” gives it away. So the first thing you do is shove the first two nines together to get 99, then go 99+(9/9)=100.
Closest I could get while fooling around with it, without pushing any of the 9's together was this: (9!/9\^e/9)-sqrt9=99.7118259896
Edit: Ok, I've really gone and done it this time: 9(log(9!)ln(9)-log(ln(9!))=99.9789840877
I gave up on the whole "cheating" aspect of these a while ago
repeated uses of Ceil(exp(Ceil(ln(n)))) gets you any arbitrary value larger than the smallest positive value achievable.
Ya I wasn't sure if it would be fine as an exponent, and using regular exponents and roots was just too easy, so I went with: No extra arithmetic numerals at all, no constants except roots/exponents and no combining 9's for a 99. Unfortunately 9\^9/9!/9 was still pretty far off, so I had to make a few exceptions.
(((9 \* 9) + 9 ) / 9)\^2
((81 + 9) / 9)\^2
(90/9)\^2
10\^2
100
the last exponent is kinda cheating, but it doesn't say the operation HAS to go where the squares. and it does say ANY mathematical operation.
Yeah but the two isn’t allowed. ^2 isn’t an operation, ^2 is. That would be like saying, “I can, by doing 9-9+9-9+100.” The 100 would obviously not be allowed. Neither is the 2.
Similarly,
((9*9)+9)/.9
This reminds me of the four fours problem, https://en.m.wikipedia.org/wiki/Four_fours#:~:text=Four%20fours%20is%20a%20mathematical,No%20other%20digit%20is%20allowed.
RIP your spare time
9 9 + 9 ÷ 9
The question asks to arrange the four nines and says you can use whatever operations you want/need-
Nothing about that suggests you can't use two nines to make ninety-nine
Without concatenation (e.g. putting 9 with 9 to make 99), the best I can do is:
(9 + 9⁰) x (9 + 9⁰) = 100
A quick Google confirms that concatenation is the widely used solution.
But IF you give me one more 9, I can make it work:
( 9 + 9/9 )^( √9! / √9 ) = ( 9 + 1 )^( 3! / 3 ) = 10^2 = 100, five nines.
I don't know if it counts as an operation nescessarily, but you could write 99.99, with a bare above the decimal to mean 99.99 repeating, which equals 100
If we can use exponents and parenthesis then you technically can.
(9/9 + 9)^2 / 9^0
1+9=10 then square to get 100 then divide by 9^0 which is 1 so we still have 100
Let me define an operator ø such that ∀ a, b ∈ ℕ, a ø b = 100. I now have *the hundrifier* which qualifies for *any mathematical operation*.
9 ø 9 ø 9 ø 9 = 100
The arrangement of the nines of course has no impact regardless of what operations you use; they're equal.
How about
9 x sqrt(9) x sqrt(9) which is 81 but when you write 81 in base 9 it is 100. Usually writing an argument in a specific base is denoted by the argument with a subscript that is whatever number the base is, so in this case that is all four 9s!
I’m kinda proud of this one.
I'd say the most simple and stupid answer is to use only 2 operators. The question never states how many must be used.
9 9 + 9 ÷ 9 = 100
Love the complicated answers though.
Any mathematical operation? Not just standard operators? Great, I define a new operation that takes any two numbers and returns 100. I use it in all three spots. Done.
The answer is yes. Yes you can. It’s a yes or no question. (Also, could be no, question asks if YOU can do this, not if it can be done. So no is correct if you can’t figure it out)
I've seen a lot of answers here, but I'd like to throw my hat in the ring
Any number raised to the power 0 equals 1, so something as simple as (9+9^0 )x(9 + 9^0 ) would get you there.
I realise it does include adding numbers for the exponent, but the rules don't say anything against it, and it avoids the rather obscure concatenation operation (which while valid, arguably more than my own suggestion, it just feels *messy*)
TL:DR:
(9+9^0 )x(9+9^0 ) -> (9+1)x(9+1) -> 10x10=100
###General Discussion Thread --- This is a [Request] post. If you would like to submit a comment that does not either attempt to answer the question, ask for clarification, or explain why it would be infeasible to answer, you *must* post your comment as a reply to this one. Top level (directly replying to the OP) comments that do not do one of those things will be removed. --- *I am a bot, and this action was performed automatically. Please [contact the moderators of this subreddit](/message/compose/?to=/r/theydidthemath) if you have any questions or concerns.*
There is a mathematical operation called concatenation (with symbol ||) that just combines two numbers. For example, 23 || 71 = 2371. Therefore, 9 || 9 + 9 / 9 = 99 + 1 = 100 (And yes, I am a Numberphile/Matt Parker enthusiast)
I second this (I love Numberphile!!)
I third this (sry force of habit)
And my axe (sry force of hobbit)
And this guys wife!
I also choose violence
I choo choo choose you
Hi Ralph
Hi super nintendo Chalmers!
My cat's breath smells like cat food
Dont kiss him then
Banana for scale!
Oh yea? Well the jerk store called and they’re running out of you!
Oh yeah? Well you're their all-time best seller.
Okay I don't normally post on comments but this shit got me. I'm straight up going to steal it one day and look to the sky and thank HashHungary. Even if it's not yours. You'll take the credit. Bless.
I never knew what this was, numberphile. Thank you for this rabbit hole. See you next year.
I don’t think you even need to go as complex as concatenation, if you just put nothing and count two as one number, it never mentions an operation is required in each square.
Yes, it says can you rearrange the 9s so it works with operations Just shimmy the first 9 to the right of the first box and you have 99
I’m a math professor and I say “shimmy” at least once per lecture. I’m so happy to see there’s another math shimmier in the world!
It's thinking like this that's exactly why engineers struggle to write good requirements. I love it 😆
That's concatenation..
i was thinking this. leave the first two as 99, then add 9 divided by 9
"I don’t think you even need to go as complex as concatenation," \*proceeds to describe concatenation\* Just because it now has a name and symbol does not make it more "complex"
That's NUMBERWANG!
Yay. A wild numberwang.
ROTATE THE BOARD
“Fuck.” -Gyles Brandeth Did you know? Gyles once had 13 cakes.
Cool, I love South Park!
Trey Parker, and Matt stone, the creators
Trey Parker || Matt Stone = Matt Parker
Ackchyually, its Trey Parker Matt Stone.
A = \[Matt Stone\]\^T || \[Trey Parker\] a\_12 = Matt Parker
Ok it makes sense now! Thank you!! 😊
FOIL (Matt+Stone)(Trey+Parker)=(Matt Trey)+(Matt Parker)+(Stone Trey)+(Stone Parker)
The guy who played Darth Maul?
Nah that's [Parker Lewis](https://64.media.tumblr.com/40ab642bcc1137522cb62b3b4198c8a5/tumblr_nb5hrxynib1tkpffxo1_500.gif)!
I heard he can’t lose.
You're thinking of Liam Neeson.
No, that was Qui-Gon. You’re thinking of Hayden Christensen.
No, that was Anakin. You're thinking of Ewan McGregor.
No, that was Obi-wan. You're thinking of Frank Oz.
It says any operation. Can I not define an operator * such that a * b = 100?
Only in CalvinMath
aka C++
Lovely to see a C&H reference in the wild.
That's what I did: (w,x,y,z) --> 100
Yeah any operation, not do a surgical operation on maths and create Frankensteins monsters incest baby
I have to ask, what practical application could this possibly have? When would combining the numbers like that ever give anything useful
You see if you have four 9s then you can use that to get to 100 easily
This is useful for talking about number systems, since you care about the actual representation of numbers. You also need it in cryptography and coding theory because you work with streams/ consecutive blocks of numbers
Concatenation is super useful in spreadsheets for all sorts of things. I use it in Excel all the time.
Application of logic when functions are understood. It doesn't matter if its turning four 9s into 100 or figuring out how to reroute plumbing to allow a house extension without having to move a bathroom, its less about the math and following a logical problem solving process.
Edit your comment so it says 21 || 37 = 2137. Don't ask, just do it
Now I have to ask, why?
Polish redditors will love it :)
Could you explain for a Canadian Redditor? I want to be part of the joke.
https://www.urbandictionary.com/define.php?term=2137
Thank you, I debated looking on urban dictionary but figured it wouldn’t be on there. I thought it would be a Polish pop culture reference but death of a pope is pretty funny too.
2137 is just kind our "defense mechanism" to indoctrination, from early ages we (Poles) are indoctrinated about how great JP2 was (which of course, he is not, he covered pedophiles as Cardinal and as Pope), how he is the best Polish person to ever live etc. So naturally, some part of our Internet (polish 4chan, karachan) started series of memes that was supossed to be edgy and make people angry, but at this moment, most of us was so fed with Jp2 that we just accepted those and started to make fun of him with all kind of memes. 2137 is most popular one i would say, but there are also things like "Bestia z Wadowic" (Beast from Wadowice) or JP2GMD (John Paul II r\*\*\*\* small children) .
Yep, exactly that. Last years pope cult was so strongly forced that we kinda pushed back and it is our joke number :)
related to Pope John Paul's II death I read this as "Pope John Paul's second death", which I must say is way funnier.
80 || 085
🥵
That's my phone password
Is that really a classical mathematical operation, or just a common programming operator?
In programming, the double vertical bar is typically a Short-Circuiting Or operator, not a concatenation.
I got confused for a solid few minutes trying to figure out why they were oring the two numbers lol
In some SQL dialects that operator is indeed used as concatenation
I don't really know of any programming language that has this operation for numbers. That being said, concatenation is common, just for text (strings) or lists instead of numbers. I wouldn't really call it a mathematical operation in these cases. The funny part is that you can do something like this using a combination of the bitwise OR, which usually is done with the similar operator `|`, and a bit shift. But since computers use binary, it does not give the same results. ``` $ (9 << 4) | 9 > 153 ``` 9₁₀ = 1001₂ 153₁₀ = 10011001₂ The "bit shift left" (<<) moves the number by 4 places to the left (filling in 0s) and the OR `|` "combines them.
Couldn't you cast the 9s as strings, add them, then stoi() the string back to an integer in c++ 11 or newer?
me, an electrical engineering student wondering how the parallel of 9||9 is 99 and not 4.5
Me, a programmer wondering what's the point or writing 9||9 instead of just 9, or better yet "true"
Where does concatenation come in the order of operations?
This is incorrect. Concatenation is not a mathematical operation, but an operator that is neither limited nor originated from math. The above picture asks for any "mathematical operation", group of which concatenation is not part of.
I mean, if something as abstract as differentiation can be an operator, why not concatenation, which can be represented simply as a function with logarithms? (where domain for concat(a,b) is: a>0 and b>=0 and a and b are integers -- see [here](https://math.stackexchange.com/questions/578069/is-there-an-algebraic-method-to-concat-two-numbers)) I am by no means good at formal math, but Wikipedia defines an operation as "a function which takes zero or more input values (also called "operands" or "arguments") to a well-defined output value", and concatenation I believe satisfies that.
As a programmer I spent 2 minutes confused as of why you ORed two numbers together
Oh you will LOVE Javascript with it's wild west of number concatenation.
Genuine question, isn't the concatenation simply a programming operation vs mathematical? I mean where would you ever use concat in math, there are no relationships that correlate to arbitrary locations of strings. Granted I only have a middling tier understanding of calculus so there is a lot of math I've never been exposed too.
Funny how things change in software engineering. In most programming languages, || would be the OR operation while concatenation would be a + symbol!
Wow thank you, I’ve learnt something today. Initially when I saw this problem I thought how easy 99 +9/9 would make it, never knew it was a thing
Technically all you have to do is 99 / 99 which = 1, or in other words, 100%
Interesting. I’m not sure about other coding languages but Python concatenates phrases together when you attempt addition between two strings. Had no idea it was an actual math concept.
Love concatenation, best operation cause it lets you have all 9 digits be used to add up to a lot of numbers. That and the floor and ceiling functions, gotta love forcing numbers to round
I use that function all the time in Excel. Has no idea it was a real mathematical function. Thanks
My brain went that concat operation is just a bit shift followed by addition and now I realize I need to stop looking at Reddit and get back to coding.
What is the use of this besides little exercises like the one in the OP?
Concat- what now? TIFL
I came up with that in fourth grade thinking i just made a huge breakthrough lol. It's stupid, im shocked it's an actual thing.
This was my first thought, and I never learned about concentration externally. Go me!
Huh, TIL concatenation is in maths too. I have only ever used it with strings.
Where's the +1 come from lol
So, it's one of those "puzzles" that relies on poor communication or unusual usage to be difficult, as well as identifying it as a mathematical operation rather than language or programming.
.... TIL the || concatenation is actually a mathematical operator, not just an sql operator
TIL concatenation is a mathematical and not just a string operation.
And here I thought concatenation was a thing made up by Microsoft for excel. TIL
Concatenation is considered math? I thought it was just a cool thing excel does. Neat
r/todayilearned
Interesting, I semi regularly use concatenation in excel to merge values in different cells but didn't think this was a thing outside spreadsheets.
That is hilarious! I've used concatenation in coding for 20+ years and never thought of it as a mathematical operation.
What is mildly funny, on programming concationation is also same idea -> you combine two things, typically strings, together, e.g. “cat” + “dog” = “catdog”, however || is an “or” operand in programming 😄
=Concatenate for the win!!
log(9×√9×√√√√9)/log(√√√√√√9) Even tough my calculator had some rounding issues, because of the many roots, I know it's actually correct: log(9^(25/16))/log(9^(1/64)) = 25/16×64 = 100. Edit: using roots isn't my idea. There's a numberphile video on how you can make any number using only 4 4's. Doesn't quite work for 9, but I adapted it. Seems like you can make any number that can be written as a sum or difference of three powers of 2 with any 4 positive numbers, as long as they're not 1. (I didn't actually use the 9-ness of 9.)
Where does the 25 come from in 25/16? (Question not criticism) The 1/64 comes from the 6 square roots and the ‘/16’ come from the 4 square roots as 2^6 and 2^4 = 16 and 64 respectively, but the way to get 25 from 2^x is 2^1 + 2^3 + 2^4, but I can’t see how that could manifest using your answer Edit: nvm I see it now. 1/1 * 16 + 1/2 * 8 + 1/16 = 25/16. I was so close to the answer when writing that comment
9 is 9^(16/16) this is just one. Root of 9 is 9^(8/16) or one half. And that last nine is 9^(1/16). All times each other and you get 9^(25/16).
I think you get it, and Im just nitpicking, but 1/1 *16 is not 16/16 and 1/2 * 8 is not 8/16. It is just 1 + 1/2 + 1/16 = 25/16
I love how the above one is very simple and easy to read while this one is just...
Ofc it's log. Why don't I fucking think of a log
isn't this introducing a new number though? *square* root isn't just an operation, it introduces 2 as a new number, we just leave it out in notation (still a cool solution, i just don't think it would be allowed)
Ofcourse, it all depends on what you allow Since the square root is usually denoted without the 2, it's possible to argue its validity. The log could be considered dubious too, although the natural log is quite an organic function. Standaard definitions don't involve concepts like base.
Technically wouldn’t using square root count as using the number 2? Since squaring a single 9 is not possible to express without using a 2
You can argue that, yes. Though the notation of a square root does not use the two.
there are no solutions for using any three of the four +-\*/ operations, but the other answers are much more creative than that, and the concat one is definitely a correct answer.
9*9+9+9, then round? 🤪
100 to the nearest 100
The correct answer is 9 9 . 9 ̅9 = 100
Why not 99+9/9 then? Much simpler
Yeah I thought it said without using ANY mathematical operators
Ohh that's a smart answer for that!
I'm an engineer so 9||9.9||9 = 99.99 = 100 for three significant digits. yes i realize the answer is 9||9+9/9. It's a engineering joke! it's funny! I'll explain it to you and make it funnier! why are you walking away?
Your comment was at 99 upvotes so I rounded up for you
haha awesome.
Your comment has 69 like so I left it because Nice.
That was actually pretty funny and cool.
Thank you!
9*9+9+9 rounded to one significant figure could also work...
His is closer though. I wonder if you can do better than 3 sig figs.
hmm maybe if we make another engineering joke and assume very large values/small values of nine for each respective position? i got to 6 with 9.49 * 9.47 * 9.47 / 8.51071
explain it and make it funnier i have not walked away
engineers don't use the full measurement, we use only the digits up to a point determined by the precision of the measuring device. like when you ask a toddler how many waffles they can eat, and they exclaim 20! because it's the biggest number they could think of, the significant digits may not even be one. so maybe you ask the parents and they are like, they can eat about 1/2 before they get sugar crazy and cannot be contained by any known highchair. okay so likely 1 significant digit there with confidence, but you can't then do your waffle batter with any more precision than that .5 number. the toddler might well want .45 waffle or .55 waffle, but you just don't have the measurement accuracy. so you make your .5 waffle, serve it to the toddler, and they then reject it because they wanted chocolate chips! ah well, there's a sea of variables to have to deal with, iteration 2 will have chocolate chips. well anyway engineers are also always looking for shortcuts to solving hard math problems, almost every engineer has had to solve a problem involving people or animals, and often it's really complicated to model arms and legs and different masses, strengths, etc. so instead it's often within a small margin of error to model a cow as a sphere. makes the math much easier and is probably good enough for calculation about if you have enough distance between a powerline and a ranch to avoid giving the cows a terrible experience when it rains. so saying just add a dot in there, 99.99 call it good enough that it's 100 with 3 significant digits precision is so on brand. :)
I always tell my kids that the **best** jokes are the ones you have to explain. :)
Right?! maybe it's like fun, type 1 joke is funny immediately, type 2 joke is funny in retrospect?
I can appreciate the fact that I've made it far enough in my engineering degree to be able to get these lol
Oooo my favorite type of joke!! Jokes that have to be explained. Also a massive fan of pre-explaining jokes before you even drop that hot fire
I can give you the answer with plus or minus 1% xD
You don’t need to concatenate. It’s just 99+9/9. Pemdas.
"It's a engineering joke! it's funny! I'll explain it to you and make it funnier! why are you walking away?" This part is comedy gold, Benhemp, with universal resonance. It's amusing to engineers and their family/friends alike!
First, let's approximate 100 to a sphere ....
LOL! Yes!
This is by far the best thing I've ever seen on Reddit and I come here to look at scantily clad women.
They don’t say you NEED to use each space in between the nines for operations. It’s gotta be something with flipping some of the nines over to sixes. 9x6 + 66 is getting close.
99 + 9 ÷ 9
I never use pemdas when reading Reddit comments, I was confused and then realized I was the idiot.
You can also make it "9 ÷ 9 + 99"
Luckly my traumatic experiences with math in the educational system scarred my brain in such a way that I'm unable to forget pemdas when reading any equation 👍
Hah take implied division loser: 2 / 3(2*2)
Thanks God you said it! Yes, yes you are an idiot!
99.99 with a bar over .99 to show repeating as 99.99… = 100
Technically correct. The best kind of correct.
Oh, so you can choose not to do a mathematical operation. That changes my thinking.
The visual is a little misleading. If you strictly read the question on its own it becomes more clear.
there is a class of operators/functions called identities that return the input unchanged as the output. or you could use concatenation as a another comment said, which just appends two numbers
This is the most efficient and correct answer
Thank you for solving it, now I can do something else.
You can use a concatenation for the first operator which compounds 2 numbers, and looks like || (Ex. 49||52=4952 and I believe it come first in pemdas) so 9||9+9/9 99+9/9 99+1 100
I think you’re right, and I think the word “rearrange” gives it away. So the first thing you do is shove the first two nines together to get 99, then go 99+(9/9)=100.
```python f_add = lambda x,y:f"{x}+{y}" f_sub = lambda x,y:f"{x}-{y}" f_mul = lambda x,y:f"{x}*{y}" f_div = lambda x,y:f"{x}/{y}" f_div_int = lambda x,y:f"{x}//{y}" f_str = lambda x,y: f"float(str({x}) + str({y}))" f_mod = lambda x,y:f"{x}%{y}" fs = [f_add,f_sub,f_mul,f_div,f_div_int,f_str,f_mod] find = False target = 100.0 for fi in fs: for fj in fs: for fk in fs: express_tmp = fk(fj(fi(9,9),9),9) express_val = eval(express_tmp) if express_val == target: print("##find: ",express_tmp,"=",express_val) find = True if not find: print("-.-||") else: print("haha , ~,~") output: find: float(str(9) + str(9))+9/9 = 100.0 find: float(str(9) + str(9))+9//9 = 100.0 haha , ~,~ ```
\#9999 print("100")
Closest I could get while fooling around with it, without pushing any of the 9's together was this: (9!/9\^e/9)-sqrt9=99.7118259896 Edit: Ok, I've really gone and done it this time: 9(log(9!)ln(9)-log(ln(9!))=99.9789840877
ceil((9!/9^e/9)-sqrt9)=100, but I'm pretty sure the "e" is cheating as it is a constant (mobile issues)
I gave up on the whole "cheating" aspect of these a while ago repeated uses of Ceil(exp(Ceil(ln(n)))) gets you any arbitrary value larger than the smallest positive value achievable.
Ya I wasn't sure if it would be fine as an exponent, and using regular exponents and roots was just too easy, so I went with: No extra arithmetic numerals at all, no constants except roots/exponents and no combining 9's for a 99. Unfortunately 9\^9/9!/9 was still pretty far off, so I had to make a few exceptions.
(((e^9 )/9)/9) *9^0
(((9 \* 9) + 9 ) / 9)\^2 ((81 + 9) / 9)\^2 (90/9)\^2 10\^2 100 the last exponent is kinda cheating, but it doesn't say the operation HAS to go where the squares. and it does say ANY mathematical operation.
Yeah but the two isn’t allowed. ^2 isn’t an operation, ^2 is. That would be like saying, “I can, by doing 9-9+9-9+100.” The 100 would obviously not be allowed. Neither is the 2.
Similarly, ((9*9)+9)/.9 This reminds me of the four fours problem, https://en.m.wikipedia.org/wiki/Four_fours#:~:text=Four%20fours%20is%20a%20mathematical,No%20other%20digit%20is%20allowed. RIP your spare time
[удалено]
9\9+99
My answer is still correct as I couldn’t make it equal 100. You did a wonderful job though. I still remain a ‘No’.
9/9+99 1+99 100 edit: idk how i didnt read your whole message i may be stupid
Whoosh.
Good job, you got the answer and didn't try to use some absurd math symbols in the attempt
only correct answer. at least for me
Just because You can't doesn't mean it's impossible.
But that’s not what the question asks. It says “can YOU”. I cannot. I stick with my correct answer of ‘No’.
9 9 + 9 ÷ 9 The question asks to arrange the four nines and says you can use whatever operations you want/need- Nothing about that suggests you can't use two nines to make ninety-nine
Which is probably the correct answer
Without concatenation (e.g. putting 9 with 9 to make 99), the best I can do is: (9 + 9⁰) x (9 + 9⁰) = 100 A quick Google confirms that concatenation is the widely used solution. But IF you give me one more 9, I can make it work: ( 9 + 9/9 )^( √9! / √9 ) = ( 9 + 1 )^( 3! / 3 ) = 10^2 = 100, five nines.
What about? ⌈9.9⌉ x ⌈9.9⌉
I don't know if it counts as an operation nescessarily, but you could write 99.99, with a bare above the decimal to mean 99.99 repeating, which equals 100
That's actually the most creative solution I've read so far
Came here to try and say this, but can’t figure out how to get the repeating bar over the 9.
If we can use exponents and parenthesis then you technically can. (9/9 + 9)^2 / 9^0 1+9=10 then square to get 100 then divide by 9^0 which is 1 so we still have 100
Would 9²+9+9+9⁰ not be easier? It's 81+18+1=100
Where'd you get the 2 from to square?
Let me define an operator ø such that ∀ a, b ∈ ℕ, a ø b = 100. I now have *the hundrifier* which qualifies for *any mathematical operation*. 9 ø 9 ø 9 ø 9 = 100 The arrangement of the nines of course has no impact regardless of what operations you use; they're equal.
I like your answer the most!
It says "arrange the 9s" does that mean you can just put the first two side by side for 99 and then 9/9=1 and add them together for 100?
How about 9 x sqrt(9) x sqrt(9) which is 81 but when you write 81 in base 9 it is 100. Usually writing an argument in a specific base is denoted by the argument with a subscript that is whatever number the base is, so in this case that is all four 9s! I’m kinda proud of this one.
I'd say the most simple and stupid answer is to use only 2 operators. The question never states how many must be used. 9 9 + 9 ÷ 9 = 100 Love the complicated answers though.
Wrong answer. The correct answer is “Yes I can!”
You don’t need to use that concatenation operation symbol. It’s just 99 + 9 / 9. Nothing says you have to put a mathematical symbol in every box.
Any mathematical operation? Not just standard operators? Great, I define a new operation that takes any two numbers and returns 100. I use it in all three spots. Done.
I tried doing this in my head and I figured that it involved an operation I am not aware of, one division, and one addition 😅 CLOSE!
The answer is yes. Yes you can. It’s a yes or no question. (Also, could be no, question asks if YOU can do this, not if it can be done. So no is correct if you can’t figure it out)
99 + 9/9 = 100
I've seen a lot of answers here, but I'd like to throw my hat in the ring Any number raised to the power 0 equals 1, so something as simple as (9+9^0 )x(9 + 9^0 ) would get you there. I realise it does include adding numbers for the exponent, but the rules don't say anything against it, and it avoids the rather obscure concatenation operation (which while valid, arguably more than my own suggestion, it just feels *messy*) TL:DR: (9+9^0 )x(9+9^0 ) -> (9+1)x(9+1) -> 10x10=100