What are two numbers that have 5 as their greatest common multiple?

Answer 1

There are no such numbers because there is really no such thing as a "greatest common multiple". If the numbers have 5 as a common multiple then 10 will also be a common multiple and clearly, 10 is greater than 5. So 5 cannot be the greatest common multiple. In fact, once you find the least common multiple of a set of numbers, you can keep adding the LCM to itself over and over again. Each new number you get will be a common multiple of your set of numbers, but each new number will always be larger than the previous. This means that you can keep adding while the number approaches infinity and you will still never find a greatest multiple.

Answer 2

There are none. The greatest common multiple of any set of integers is infinite.