 # Perform Math Operations in Python

Published 5 years ago
Updated 3 years ago

This lesson will introduce arithmetic operations in Python. In addition to basic addition, subtraction, multiplication, and division, you will learn about the differences in division between Python 2 and Python 3.

Math operations in Python are pretty straightforward. We can say 3+4, and it returns a sum. We can do 3-4, same as 3*4, and can even do 3 mod 4. Those all work the same between Python 2 and Python 3.

Division is a little bit different. In Python 2, if I do 3/4, I get 0. It rounds that to an integer. If I wanted to see the complete value, I need to include the period or dot at the end, and it returns 0.75. Let me show you that in Python 3, by actually typing the Python 3 command.

In Python 3, if I do 3/4, I get 0.75. If I wanted that rounded to an integer, I can use double slashes, and that returns 0. This works for variables, too. I can create a variable, a, and set it to 3. I can set b = 4. If I do a+b, it returns 7. If I do a/b, it returns 0.75, or a//b, and it returns 0.

Quick note on naming variables in Python. There are some recommendations here, that they are all in lowercase. We could say sum=3+4, or if there is multiple words, it's recommended that they are separated by the underscore.

Finally, it's recommended that variable names don't start with a number. That would not be a recommended variable name in Python.  Stephen James
~ 4 years ago

/ and // don't round they truncate.  Will Buttoninstructor
~ 4 years ago

Good catch! I'll get that corrected!