this post was submitted on 31 May 2025
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A fake Facebook event disguised as a math problem has been one of its top posts for 6 months (www.engadget.com)
submitted 10 months ago by Obelix@feddit.org to c/technology@lemmy.world
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[–] vithigar@lemmy.ca 6 points 10 months ago (35 children)

The same priority operations can be done in any order without affecting the result, that's why they can be same priority and don't need an explicit order.

6 × 4 ÷ 2 × 3 ÷ 9 evaluates the same regardless of order. Can you provide a counter example?

[–] HereIAm@lemmy.world 5 points 10 months ago* (last edited 10 months ago) (27 children)

So let's try out some different prioritization systems.

Left to right:

(((6 * 4) / 2) * 3) / 9
((24 / 2) * 3) / 9
(12 * 3) / 9
36 / 9 = 4

Right to left:

6 * (4 / (2 * (3 / 9)))  
6 * (4 / (2 * 0.333...))  
6 * (4 / 0.666...)  
6 * 6 = 36

Multiplication first:

(6 * 4) / (2 * 3) / 9  
24 / 6 / 9

Here the path divides again, we can do the left division or right division first.

Left first: 
(24 / 6) / 9  
4 / 9 = 0.444...

Right side first:  
24 / (6 / 9)  
24 / 0.666... = 36

And finally division first:

6 * (4 / 2) * (3 / 9)  
6 * 2 * 0.333...  
12 * 0.333.. = 4

It's ambiguous which one of these is correct. Hence the best method we have for "correct" is left to right.

[–] vithigar@lemmy.ca 5 points 10 months ago (1 children)

I stand corrected

[–] SmartmanApps@programming.dev 0 points 9 months ago

I stand corrected

No, you weren't. Most of their answers were wrong. You were right. See my reply. 4 is the only correct answer, and if you don't get 4 then you did something wrong, as they did repeatedly (kept adding brackets and thus changing the Associativity).

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