Question

How do you find the LCM of 7 and 9?

Answer 1

63

Explanation:

Since the only number that `7` and `9` go into evenly is `63` we must consider this simple step:

`7*9=63`

A least common multiple is the smallest unit that both numbers can evenly be divided by. Since you can evenly divide `63` by both `7` and `9` the following is true:

`63` is the least common multiple of `7` and `9`.

Answer: 63

Answer 2

`LCM = 7 xx9 = 63`

Explanation:

`7 and 9` have no common factor (apart from `1`).

Therefore the `LCM` must contain the whole `7` and the whole `9`.

`LCM = 7 xx9 = 63`

This is clear if we write `7 and 9` as the product of the prime factors:

`" "7 = 7`
`ul(" "9= " "3xx3)`

`LCM = 7 xx 3xx3 =63`