Answer
1 is considered all three types of numbers: natural, integer and whole number
Work Step by Step
Natural Numbers: N = {1, 2, 3, 4, 5, ...}
Integers: I = {..., -3, -2, -1, 0, 1, 2, 3, ...}
Whole : W = {0, 1, 2, 3, ...}
The number 1 is in each set.
