Write all natural numbers less than 100 which are common multiples of 3 and 4.

The common multiples of 3 and 4 are the multiples of LCM(3, 4) = 12.

Multiples of 12 less than 100 are: 12, 24, 36, 48, 60, 72, 84, 96.

Hence, the natural numbers less than 100 which are common multiples of 3 and 4 are 12, 24, 36, 48, 60, 72, 84 and 96.