The unit's digit in the cube of 2, 16, 20 is always _____.
Even
23 = 2× 2 × 2 = 8
163 = 16× 16 × 16 = 4096
203 = 20× 20 × 20 = 8000
As 2, 16, 20 are even numbers and the cube of an even number is always even , the unit's digit of the cubes of the given numbers are even.