the first two common multiples of 15,27 are 135,270
15 and 30
Two common multiples of 21 and 15 are 105 and 315.
Since 3 and 5 are both prime numbers, the only common factor of the two numbers is 1. Perhaps you are thinking of common multiples, the first two common multiples of the two numbers are 15 and 30.
The two common multiples of three and five are: 15 and 30 ^-^
Since 3 is a factor of 15, the first three common multiples of 3 and 15 are 15, 30, and 45.
60
75
15 & 20 have an infinite number of Common Multiples; the first three are 60, 120 and 180.
The multiples of 12 are 12, 24, 36, 48, 60... The multiples of 15 are 15, 30, 45, 60... 60 is the LCM of 12 and 15 because it is the first common multiple of these two numbers.
15, 30, 45
105 and 210 are.