Multiples of a number are the numbers which are exactly divisible by the given number.
Multiple of 6 = 6, 12, 18, 24, 30, 36, 42, 48, 54, 60, 66, 72, …………
Multiple of 8 = 8, 16, 24, 32, 40, 48, 56, 64, 72, …………………….
Thus, first three common multiples of 6 and 8 = 24, 48, 72