CS105: Introduction to Python

Like addition and subtraction, multiplication and division will look very similar to how they do in mathematics. The sign we'll use in Python for multiplication is * and the sign we'll use for division is /.

Here's an example of doing multiplication in Python with two float values:

k = 100.1
l = 10.1
print(k * l)

Output:

1011.0099999999999

When you divide in Python 3, your quotient will always be returned as a float, even if you use two integers:

m = 80
n = 5
print(m / n)

Output:

16.0

This is one of the major changes between Python 2 and Python 3. Python 3's approach provides a fractional answer so that when you use / to divide 11 by 2 the quotient of 5.5 will be returned. In Python 2 the quotient returned for the expression 11 / 2 is 5.

Python 2's / operator performs floor division, where for the quotient x the number returned is the largest integer less than or equal to x. If you run the above example of print(80 / 5) with Python 2 instead of Python 3, you'll receive 16 as the output without the decimal place.

In Python 3, you can use // to perform floor division. The expression 100 // 40 will return the value of 2. Floor division is useful when you need a quotient to be in whole numbers.