this post was submitted on 31 May 2025
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[โ€“] HereIAm@lemmy.world 11 points 1 month ago (38 children)

The issue normally with these "trick" questions is the ambiguous nature of that division sign (not so much a problem here) or people not knowing to just go left to right when all operators are of the same priority. A common mistake is to think division is prioritised above multiplication, when it actually has the same priority. Someone should have included some parenthesis in PEDMAS aka. PE(DM)(AS) ๐Ÿ˜„

[โ€“] vithigar@lemmy.ca 6 points 1 month ago (32 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 ร— 4 รท 2 ร— 3 รท 9 evaluates the same regardless of order. Can you provide a counter example?

[โ€“] HereIAm@lemmy.world 5 points 1 month ago* (last edited 1 month ago) (24 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.

[โ€“] vithigar@lemmy.ca 5 points 1 month ago (1 children)

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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