<3

I understand why this is wrong (order of operations dictates the division happens first, so it's really 25 - 1 = 24), but why is it funny? I don't mean "This isn't funny," I think I'm just missing the joke.

4! Is meant to be 4 factorial. 4! = 4 x 3 x 2 x 1 = 24
- Aha! Got it, thank you so much.
- And here I was thinking I was still decent at math. I got bamboozled...
- Or if you don’t know order of operations, then you probably also don’t know factorials, so 20 / 5 = 4
- The fuck is a "factorial"? They didn't teach me that one in high school math and I couldn't afford college.
4! Is a factorial which means it's 4 x 3 x 2 x 1 = 24
- Totally missed that. Thank you.
4 factorial
The exclamation point denotes the factorial function. 4! = 4 ⋅ 3 ⋅ 2 ⋅ 1
I see no one has explained yet, so I'll give it a shot. He is excited about math, and that needs to be encouraged.
The exclamation point makes it right. The formula, when worked with proper order of operations, equals 24, which is equal to 4 factorial (4!) 1 * 2 * 3 * 4=24
Cause math people has a weird humor?

Best math meme so far.

4! = ...Wait, that's literally the point of the post this time

Unexpected expected factorial
- Unexpected incorrect answer in comments

ASCII hack failure of language. Even in mathematics, ! has multiple meanings like with Boolean NOT. We need a science, math, and language reformation to remove non intuitive narcissistic names, and implied contextual meanings.

You might find Lojban interesting if you are not already aware. (I haven't tried to learn it myself, I just know it exists)
- Relevant xkcd
  https://xkcd.com/191/
- If someone wants to start a Lojban pun community, I would definitely subscribe just to learn about Lojban.
  Although, if no one posted in the community, I wouldn't be sure if it was a perfectly logical language or the community was just dead.
I believe you mean, "nice pun!"
I've never seen ! used for boolean NOT in maths, just ¬. I think ! is something programming languages went for because it's easier to type. That said, screw (a, b). Is that a (coordinate) pair, an interval, an inner product, some secret fourth thing? Who knows!
- Inner products are written as ⟨a,b⟩, no? Fair point on the interval, tho

Comment section full of people looking for an opportunity to argue

Ok this is funny

You got the wrong symbol in the headline, it should be >3

This is quite possibly the best maths joke I've ever seen.

[edit] I guess it still can't beat the 'be rational' / 'get real' one.

Thank God this meme is muted

Clever! lol

for those that didn't get it: clever factorial = brilliant

Promptly Evacuate Manure Drain And Septic

The answer in the comic is correct. It's just written in a way to make you as the reader think he's got it wrong for a second.
The ! operator in mathematics indicates a function called a factorial. Four factorial, or 4! = 4 × 3 × 2 × 1 = 24. Which is the correct answer if you follow the proper order of operations.

Can someone explain to me why this is funny?

So with people who do order of operations incorrectly, you have 25-5 =20 and then divide it by 5 and you get 4.
However the correct answer is 24 since you do the division first.
Where the joke comes in is he states “4!”, which sounds like he is emphatic about the wrong answer. However an exclamation mark is “factorial” which translates to 4x3x2x1… which happens to equal the correct answer of 24.
- Ah! :D I like it.

5-5/5 != 4

007 will never get this wrong, it's 4, 24.

3

:3

25 - ⁵/₅ = 25 - 1 = 24

If you wrote it vertically:

25 - 5
\ ————— = 4
\ 5

But once you lay it out on one line, you have to use prins to prioritize addition / subtraction:

(25 - 5) / 5 = 20 / 5 = 4

Some YouTube mathematicians deep-dive into this.

ETA: Nothing goes over my head! My reflexes are too fast, I would catch it.

The joke is 4! (Factorial) Is 24 so it looks right even if you do order of operations incorrectly.
- Ok so I'm not dumb! Usually I am with math but I got this one. Go me!
Yeah and 24 = 4 factorial = 4!

My favourite kind of nerd.

#DAMN YOU MATHEMATICIANS! YOU GOT ME AGAIN!!!

Nerds!

(Im just mad cuz i can't do math. Carry on... Nerds)

It's about time there was a real argument in here

user has left the channel

Jokes and tricks that hinge on unclear communication (eg: not using parenthesis or other notation to make intent clear), and then are smug when people are tricked, remind me of the old xkcd https://xkcd.com/169/

I just saw some jokes about factorials so at least I got this one, heh.

Sorry but what is unclear in OPs image?
- 25 - 5 ÷ 5 when read naively left to right looks like it would be "25 - 5 = 20. Then take that and divide by 5, for an answer of 4". It would be clearer to write it as (25 - 5) ÷ 5 or 25 - (5 ÷ 5) depending on what's intended.
  You see those kind of "gotcha!" posts online sometimes, where someone posts a problem that tempts you into doing order of operations wrong.
  Someone who sees how to do it correctly immediately and thinks everyone knows that is invited to view https://xkcd.com/2501/ as well.

I’m only going to say this once but if I’m doing a sum and you want me to do it in a specific order, use brackets. That’s what brackets are for. Don’t expect me to do things in a predetermined order because I literally can’t be bothered and I will never care enough to do that. I’m already doing a sum so don’t push it, okay bud

But that's a bit like saying "If you're going to talk to me, put the adjectives before the nouns," even in Spanish where they come after. Mathematical notation is a language and it has a syntax. Sure, you can decide to ignore that syntax, or insist that people modify their use of it for you, but it's not really a reasonable expectation.
- I think this is very stupid for a number of reasons. Why is there an order of operations that supersedes the direction the operations are written in? That’s at best dim witted and at worst deliberately misleading. Grog write left to right. Grog read left to right. Grog do sum left to right.
  There is absolutely no reason in the world why anybody should have to know that division comes before subtraction. That’s fucking insane, man. What is the point of writing things down if you’re only going to do them in a set order anyway? May as well have a big jumble of letters and numbers and symbols on the page at that point, like who cares. The whole point of writing things down is to express concepts. Can’t do that with any kind of nuance if you’re going to read it one way anyway, no matter how you write it down. That would be like saying you always pronounce certain letters at the start of words even if they’re in the middle. Completely nuts.
well then you should stop doing math cuz you're doing it wrong
- Thanks I take enormous pleasure in never doing any maths at all ever, largely for reasons like this 😌

Very funny joke, but I don't agree with the division sign. Its supposed to be either a / or \ depending on which way you want to divide.

never in my life have I seen a \ division sign.
- Well it was a joke, but it seems like a lot of people did not get it.

Did nobody learn order of operations?

The meme is correct. It is 4!.
- Yeah but it's playing on the idea that the reader would think 25-5÷5 is 4. That's the joke. Without it there's no punchline.

Imma be weird and argue that the answer actually should be 4.

Dear Aunt Sally is great or whatever, but syntax also fuckin matters. We can all probably agree that the faster, more intuitive answer is obviously 4. Most of those in the western world (meme's largest audience) read left-to-right and there is nothing the delineate that division must actually come before inverse addition until one has carefully examined the entire the problem (which you should definitely be doing, dumb-dumb) and slapped on another layer of thinking (inefficient waste of time when doing quick mafs). Use the damn parenthesis, ffs!

Using parentheses where a few simple rules will do seems awfully inefficient. Both to write and to read.
- Textbook authors be like:
  sintx^{2 + cosπx}3 - 3
- I find it far more efficient to parse. I also put superfluous parenthesis in my code where I feel it helps readability.
  It's something to judge on a per-case basis, it'd also work very well to use whitespace (i.e. 25 - 5/5 instead of 25 - 5 / 5). Of course you don't want to parenthesis everything but it can help a lot.
- Simple rules are only simple if they are intuitive and consistently applicable. Otherwise, they are nothing more than yet another thing to remember and think about, yet another source of error, and yet another possible point of confusion. With enough time/ effort, one can brute force the intuitiveness, but that doesn't automatically make the rule good or universally useful.
  As a math teacher, I can assure you that not everyone has the same level of understanding or knowledge when it comes to order of operations. Some people struggle to remember the specific order, and mnemonics are worthless. Others struggle to read or visually process problems written with unclear or inconsistent symbology. Hell, most people don't even learn exactly the same fucking rules. Tell me, where is the simplicity in all of that?
  When I teach order of operations, the glass eyes and exasperated sighs of frustration come out. But when I teach just the parenthesis and exponent stuff, lightbulbs and understanding. Suddenly, people "too dumb" to do 2+2 are doing algebra and getting excited about math for the first time ever. Some of this is certainly a failing of our collective education system, but we can't just forget that everyone has their own flavor of learning disability, neuro-diversity, and life experience. Simple rules quickly fail to be simple in the face of complex people.
Following your logic,
27²+53³ becomes (2(7²))+(5(3³))
Talk about inefficient waste of time.
- I find this to be unironically both easier to read (by an incredibly wide, dyslexic margin) and faster to write and type.
  Parenthesis consists of only two symbols that only require two keyboard keys and a single stroke of a pen to write compared to the four keys and varying strokes of the standard operators (aka. more efficient). But, far more importantly for me anyway, "+", "×", "*", "÷", all look nearly identical unless I stare the keyboard or problem for an agonizing century (waste of time, perhaps?) and even then it's a mystery whether my brain processed the symbology correctly or put the numbers in the right spot to do math (yep, waste of time). The humble ( ), however, is very easy to see, and it creates neat little windows that don't leave much room for misinterpretation.
  27²+53³ = accessibility nightmare
  (2(7²))+(5(3³)) = readable with clearly defined order of operations
  I did preface this by pointing out I'm weird.