To find a common multiple of 5 and 9, we need to look for multiples of each number and identify the smallest one that they share.
The multiples of 5 are: 5, 10, 15, 20, 25, 30, 35, 40, 45, …
The multiples of 9 are: 9, 18, 27, 36, 45, 54, …
From these lists, we can see that the number 45 appears in both sequences. Therefore, 45 is a common multiple of 5 and 9.
In fact, the least common multiple (LCM) of 5 and 9 is also 45, as it is the smallest number that is a multiple of both. The LCM can be found by multiplying the two numbers together divided by their greatest common divisor (GCD), but since 5 and 9 have no common factors other than 1, we can simply multiply them: 5 x 9 = 45.