this post was submitted on 03 Dec 2023
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[–] Coreidan@lemmy.world 11 points 11 months ago (2 children)

Left to right. If you’re following ALL of the rules of PEMDAS then the answer is 16

[–] 50MYT@aussie.zone 2 points 11 months ago (4 children)

Multiplication before division bro.

The division goes last.

Answer is 1.

[–] Zagorath@aussie.zone 8 points 11 months ago (1 children)

The answer is 1, but the logic you've used to get there is a little off. Different groups actually follow different logic, but they usually arrive at the same end-point.

The American Mathematical Society goes:

  • Brackets
  • Indices
  • Multiplication indicated by juxtaposition
  • Regular multiplication and division
  • Addition and subtraction

While the American Physical Society does

  • Brackets
  • Indices
  • Multiplication
  • Division
  • Addition and subtraction

In both cases, addition and subtraction are equal in priority (this solves the problem brought up by a different comment where following primary school BIDMAS would mean 8-4+2=2). In one case (and this is the way I prefer to do it) they solve the problem by declaring that implicit multiplication is done before division, but explicit multiplication with the × sign follows the same rules you would have learnt in primary school. The other says all multiplication is done before division, including explicit multiplication.

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

follows the same rules you would have learnt in primary school

It's never that - that's how people are getting the wrong answer. In high school you get taught about The Distributive Law.

[–] NikkiNikkiNikki@kbin.social 7 points 11 months ago (1 children)

Multiplication and division have the same priority, whichever one comes first LTR is the one that gets resolved first, so it's (8 / 2) * 4

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

it’s (8 / 2) * 4

It's 8/2(2+2)=8/(4+4) or 8/2(2+2)=8/2(4)=8/(2x4)

[–] jlh@lemmy.jlh.name 5 points 11 months ago

By that logic: 8-2+4=2

Of course, it could be kind of ambiguous, but typical convention gives multiplication/division the same priority, as it does addition/subtraction.

And in general, you need to go left to right when dealing with division and subtraction, if other operations have the same priority.

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

Right answer but wrong reason. It's because distribution comes first

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

If you’re following ALL of the rules of PEMDAS then the answer is

...1. If you got 16 then there's one or more rules that you didn't obey.