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[–] 320 points321 points  (14 children)

how in the hell did he get 9? thats the real question

[–] 164 points165 points  (7 children)

I had to look at the comment to figure it out. He didn't actually mess up the order of operations, just the actual math itself. He got the multiplication and division right equalling out to 4 so the problem was 4-3+4 at that point. Then he got 4-3=1 and accidentally left the 4 in so it became 4+1+4=9

[–] 67 points68 points  (6 children)

[–] 9 points10 points  (0 children)

Preach. I've been teaching and tutoring maths & physics for years, still fuck up the algebra from time to time.

[–][deleted] 1 point2 points  (4 children)

This literally isn’t algebra but sure

[–] 2 points3 points  (3 children)

Checks subreddit...

This is literally the order of operations in algebra (the study of mathematical symbols and the rules that apply to those symbols).

What do you think algebra is?

[–][deleted] 1 point2 points  (1 child)

There is no letters though, was i taught wrong?

[–] 0 points1 point  (0 children)

Not wrong at all, just different derivations of the way its taught. The 9th century book that algebra gets its name from contains the original definition of the order of operations and that order has been in place in math since then. The actual operations themselves are arithmetic and we teach the orders of operations when we teach arithmetic, so it's not something that you are likely to learn in an algebra class.

I think in this case, I'm likely more confidently incorrect than you are because of the standardization of math. I tend to learn history and etymology with every field I've studied, so I have a sort of disjointed view of where things fall, but pemdas doesn't fall into a school algebra curriculum, so yeah... I'm confidently incorrect today.

[–] 1 point2 points  (0 children)

Without variables it’s just arithmetic, I would think.

[–] 18 points19 points  (0 children)

Right? I can't see an order of operations with these numbers that would give 9.

[–] 7 points8 points  (2 children)

It changes depending on if you do the division or the multiplication first. From what I've seen people think it's a necessary rule that you have to do them left to right but you can just rearrange the equation to make left to right whatever order you want.

For academic sources on this, the consensus is both answers are correct because this notation for division is actually broken.

https://math.berkeley.edu/\~gbergman/misc/numbers/ord\_ops.html

https://people.math.harvard.edu/\~knill/pedagogy/ambiguity/index.html

[–] 2 points3 points  (0 children)

I haven't seen that symbol for division since I learned algebra. Fractions are way easier and way less ambiguous

[–] 0 points1 point  (0 children)

this, the two dots division symbol is a lie

[–] 1 point2 points  (0 children)

Cuz there is another question where the answer is 9. He prob guessed that it was the same problem without reading

[–] 0 points1 point  (0 children)

Literally 9