Integers.

Integer ( a definition)
A -number with no fractional part. Includes the counting numbers {1, 2, 3, ...}, zero {0}, and the negative of the counting numbers {-1, -2, -3, ...} You can write them down like this: {..., -3, -2, -1, 0, 1, 2, 3, ...} Examples of integers: -16, -3, 0, 1, 198   Here we go.

Adding integers using counters

Adding integers using a number line