Write down the first 3 common multiples of 3 and 7.
Multiples of 3: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 39, 42, 45, 48, 51, 54, 57, 60, 63
Multiples of 7: 7, 14, 21, 28, 35, 42, 49, 56, 63
First 3 common multiples are 21, 42, 63
Answer(s): 21, 42, 63