What is the least common multiple of 14 and 21?
The multiples of 14 are 14, 28, 42, 56, 70, 84, and so on. The multiples of 21 are 21, 42, 63, 84, 105, and so on. I can see that 42 is the first number that is in both lists, so 42 is the least common multiple of 14 and 21. 