Question

Alicia is thinking of a number for her friends to guess. She tells them the number is the least common multiple of 3 and 7. Which number is Alicia thinking of?

Answer 1

21

Explanation:

Multiples of 3: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, ...

Multiples of 7: 7, 14, 21, 28, 35, 42, 49, 56, ...

We see that the first number that is a multiple of both 3 and 7 is 21.