Find the greatest common factor and the least common multiple of each of the following sets of numbers.
12 and 7
7 is a prime number, so its only factor other than itself is 1.
Their greatest common factor is 1. Can you find their least common multiple?
3, 15, and 9
To find the least common multiple, try finding multiples of 15 and checking
whether they are also multiples of 3 and 9.
The least common multiple is 45. Try finding the greatest common factor.
20 and 30
10 is a factor of both of these numbers.