A number line can also be used to represent both positive and negative integers as well. Writing numbers on a number line makes comparing numbers and answering math questions easier. 
We always move right to add, move left to subtract.

This set includes 12 number lines, 6 are have numbers (1-5, 1-10, 1-20) and the other 6 have no numbers.  6 cards are Addition, 6 cards are subtraction.

Dry erase marker is included.