Python double slash operator

Python’s double slash (//) operator performs floor division.

What exactly is floor division?

Floor division is a normal division operation except that it returns the largest possible integer. This integer is either less than or equal to the normal division result.

– Educative.io

In code, it looks like this:

# Regular python division
8 / 3. # 2.6666666

# Floor division
8 // 3. # 2

Some languages perform floor division by default when dividing integers, like Go and (surprisingly) Ruby. In Python, you have to use //.

Note: floor division always rounds down, not towards 0. It’s a possible gotcha if you’re working with negative numbers:

# Regular python division
-8 / 3. # -2.6666666

# Floor division always rounds down
-8 // 3. # -3

Python