precedence

Question

Hi everyone,

I really don't get this question from a python challenge:

print(int(2/2*2-2+2%2))

The correct output is 0

But why? The precedence of multiplication is higher than division, so I supposed it must be calculate in this way: (2/(2*2))-(2+(2%2))

So, where is the error in my logic?

Answer 1

2/2 = 1
1*2 = 2
2 - 2 = 0
0 + (2%2) = 0 because: 2%2 = 0

The precedence of multiplication is not higher the division.
You do them in the order they come. The correct way to add parentheses is:

((2/2)*2)-(2)+(2%2)

Answer 2

It is always relevent but the acronime PEMDAS helps you remember the rule, it is not the rule itself. It would probibly be better stated PE(M&D)(A&S)
You do parenthese, exponets, multiplication and division (starting on the left), Addision and subtraction (also starting on the left)

Answer 3

Ok, thanks. So the PEMDAS-rule (https://techvidvan.com/tutorials/JUMP_LINK__&&__python__&&__JUMP_LINK-operator-precedence/) isn't working here? Why?

Answer 4

No, if you read all of it, it clearifies

“The associative operators are division, multiplication, remainder, etc. and the expressions will be evaluated from left to right.”

Answer 5

But this doesn't explain to me why the order of PEMDAS is irrevelant. Or to ask from another direction: in which cases does the PEMDAS-rule has a meaning?