If two numbers are divisible by a number,
their difference is also divisible by the number
16 & 20 is divisible by 4
Difference = 20 − 16 = 4
∴ 4 is also divisible by 4
36 & 78 are divisible by 6
Difference = 78 − 36 = 42
∴ 42 is also divisible by 6
100 & 25 are divisible by 5
Difference = 100 − 25 = 75
∴ 75 is also divisible by 5