Y = 3x, X belongs to {0,3,6}, find the range

Y = 3x, X belongs to {0,3,6}, find the range

A range is a collection of function values
The function value of 0 is 3 * 0 = 0
The function value of 3 is 3 * 3 = 9
The function value of 6 is 3 * 6 = 18
So, the range is {0,9,18}