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Python Python Basics Types and Branching Numeric

Posted by Shukran Ali
Shukran Ali
132 Points

If in the order of operations addition comes before substraction, why didnt you add 15 with 8 first then do 10 - 23?

If in the order of operations addition comes before substraction, why didnt you add 15 with 8 first then do 10 - 23?

5 Answers

Joseph Yhu
.a{fill-rule:evenodd;}techdegree seal-36
Joseph Yhu
PHP Development Techdegree Graduate 48,635 Points

Addition does not come before subtraction in the order of operations. They have the same precedence, so the expression will be evaluated from left to right.

Shukran Ali
Shukran Ali
132 Points

Oh okay thanks because he said in PEMDAS addition comes first had me confused

Master ohm
Master ohm
40 Points
Master ohm
Master ohm
40 Points

which ever you consider , I consider BODMAS , so addition definately comes before substraction.

nicolaspeterson
nicolaspeterson
8,569 Points
nicolaspeterson
nicolaspeterson
8,569 Points

Hey Joseph could you elaborate more on this? I'm still confused even after reading your explanation, and the link in the teacher's notes didn't help.

Joseph Yhu
.a{fill-rule:evenodd;}techdegree seal-36
Joseph Yhu
PHP Development Techdegree Graduate 48,635 Points

To use his example: 10 - 15 + 8, you would do the subtraction first because it comes before the addition (i.e. 15 + 8) and addition and subtraction have the same precedence.; however, if the expression was, e.g.: 10 - 15 * 8, you would do the multiplication first because multiplication has higher precedence over subtraction.

It's helps to understand if you remember that subtraction is simply addition by a negative: 10 - 15 + 8 is the same as 10 + (-15) + 8.

Team Matrix
PLUS
Team Matrix
Courses Plus Student 456 Points
Team Matrix
Team Matrix
Courses Plus Student 456 Points

parenthesis is most powerful then exponents. Division and multiplication has same precedence. Addition and subtraction has same precedence. In case of same precedence, which operator comes first will be executed first.

ja5on
ja5on
10,338 Points
ja5on
ja5on
10,338 Points

I have this technique from https://www.mathsisfun.com/operation-order-bodmas.html

basically

B Brackets first
O Orders (i.e. Powers and Square Roots, etc.)
DM Division and Multiplication (left-to-right)
AS Addition and Subtraction (left-to-right)

Note: the only strange name is "Orders". "Exponents" is used in Canada, and so you might prefer "BEDMAS". There is also "Indices" which makes it "BIDMAS". In the US they say "Parentheses" instead of Brackets, so it is "PEMDAS"