this post was submitted on 03 Dec 2023
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[–] queue@lemmy.blahaj.zone 13 points 11 months ago* (last edited 8 months ago) (10 children)

For anyone like me who has math as their worst subject: PEMDAS.

PEMDAS is an acronym used to mention the order of operations to be followed while solving expressions having multiple operations. PEMDAS stands for P- Parentheses, E- Exponents, M- Multiplication, D- Division, A- Addition, and S- Subtraction.

So we gotta do it in the proper order. And remember, if the number is written like 2(3) then its multiplication, as if it was written 2 x 3 or 2 * 3.

So we read 8/2(2+2) and need to do the following;

  • Read the Parentheses of (2 + 2) and follow the order of operations within them, which gets us 4.
  • Then we do 2(4) which is the same as 2 x 4 which is 8
  • 8 / 8 is 1.

The answer is 1. The old calculator is correct, the phone app which has ads backed into it for a thing that all computers were invented to do is inaccurate.

[–] hallettj 2 points 11 months ago (1 children)

The problem is that the way PEMDAS is usually taught multiplication and division are supposed to have equal precedence. The acronym makes it look like multiplication comes before division, but you're supposed to read MD and as one step. (The same goes for addition and subtraction so AS is also supposed to be one step.) It this example the division is left of the multiplication so because they have equal precedence (according to PEMDAS) the division applies first.

IMO it's bad acronym design. It would be easier if multiplication did come before division because that is how everyone intuitively reads the acronym.

Maybe it should be PE(M/D)(A/S). But that version is tricky to pronounce. Or maybe there shouldn't be an acronym at all.

[–] SmartmanApps@programming.dev 1 points 8 months ago

but you’re supposed to read MD and as one step

You can do them in any order at all - M then D, D then M (hence the acronym BEDMAS), or all in one - what does matter is not treating Distribution as though it's Multiplication (which refers literally to multiplication signs), when in actual fact it's the first step in solving Brackets.

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