this post was submitted on 03 Dec 2023
407 points (99.5% liked)

196

16721 readers
2224 users here now

Be sure to follow the rule before you head out.

Rule: You must post before you leave.

^other^ ^rules^

founded 2 years ago
MODERATORS
 
you are viewing a single comment's thread
view the rest of the comments
[–] [email protected] 24 points 1 year ago (4 children)

The problem is that there's no "external" parentheses to really tell us which is right: (8 / 2) * 4 or 8 / (2 * 4)

The amount of comments here shows how much debate this "simple" thing generates

[–] [email protected] 32 points 1 year ago

When there are no parentheses, you process left to right on the same tier of operations. That's how it's always been processed.

[–] [email protected] 20 points 1 year ago (1 children)

Afaik the order of operations doesn't have distributive property in it. It would instead simply become multiplication and would go left to right and would therefore be 16.

[–] [email protected] 1 points 9 months ago

Afaik the order of operations doesn’t have distributive property in it

The Distributive Law applies to all bracketed terms that have a coefficient. It's literally the first step in solving brackets.

[–] [email protected] 10 points 1 year ago (3 children)

If you agree that parenthesis go first then the equation becomes 8/2x4. Then it's simply left to right because multiplication does not take precedence over division. What's the nuanced talk? That M comes before D in PEMDAS?

[–] [email protected] 4 points 1 year ago (1 children)

Finally someone in here who knows math. Thank you.

[–] [email protected] 2 points 1 year ago

My observation was mainly based on this other comment

https://programming.dev/comment/5414285

In this more sophisticated convention, which is often used in algebra, implicit multiplication is given higher priority than explicit multiplication or explicit division, in which those operations are written explicitly with symbols like x * / or ÷. Under this more sophisticated convention, the implicit multiplication in 2(2 + 2) is given higher priority than the explicit division in 8÷2(2 + 2). In other words, 2(2+2) should be evaluated first. Doing so yields 8÷2(2 + 2) = 8÷8 = 1. By the same rule, many commenters argued that the expression 8 ÷ 2(4) was not synonymous with 8÷2x4, because the parentheses demanded immediate resolution, thus giving 8÷8 = 1 again.

[–] [email protected] 1 points 9 months ago

If you agree that parenthesis go first then the equation becomes 8/2x4

No, it becomes 8/(2x4). You can't remove brackets unless there's only 1 term left inside. Removing them prematurely flips the 4 from being in the denominator to being in the numerator, hence the wrong answer.

[–] [email protected] 1 points 9 months ago

The problem is that there’s no “external” parentheses to really tell us which is right: (8 / 2) * 4 or 8 / (2 * 4)

The Distributive Law tells us it's the latter.