The common multiples of 3 and 7 are 21, 42, 63 and so on.
21 and 42 are.
1.draw up a chart 1-100 2.get rid of 2's multiples 3.get rid of 3's multiples 4.get rid of 5's multiples 5.get rid of 7's multiples 6. all the left over numbers are prime.
63 is the LCM of 9 and 7.
7 x 18 = 126 126 is a common multiple of 7 and 18
Any multiple of 105.
42 is the LCM of 3, 6 and 7. All multiples of 42 are multiples of 3, 6 and 7
Odd multiples of 21.
The common multiples of an set of numbers are the multiples of their lowest common multiple. lcm(7, 8, 9) = 504 → the first 3 common multiples of 7, 8, 9 are 504, 1008, 1512.
The LCM is: 21
2
There are infinitely many common multiples of 3, 5 and 7, each one 105 larger than the previous one. Or to put it another way: the common multiples of 3, 5 and 7 are the multiples of their lowest common multiple which is 105. ie their common multiples are all the multiples of 105, of which there is no end - there is an infinite number of multiples of 105 (or any other number [except zero]).
21
2,56,84
lcm(2, 7) = 14 → first 3 common multiples are: 14, 28, 42; lcm(2, 8) = 8 → first 3 common multiples are: 8, 16, 24; lcm(7, 8) = 56 → first 3 common multiples are: 56, 112, 168; lcm(2, 7, 8) = 56 → first 3 common multiples are: 56, 112, 168.