Question

How do you find the prime factorization of 20?

Answer 1

`20 = 2 xx 2 xx 5`

Explanation:

You can separate out each prime factor in turn as follows:

`20` is divisible by `2` (i.e. even) since its last digit is even.

So divide by `color(blue)(2)` to get `10`.

`10` is divisible by `2` since its last digit is even.

So divide by `color(blue)(2)` to get `5`.

`color(blue)(5)` is prime.

So we can stop and write down `20` as the product of the primes we have found:

`20 = 2 xx 2 xx 5`

This can be written as a factor tree:

`color(white)(00000)20`
`color(white)(0000)"/"color(white)(00)"\"`
`color(white)(000)color(blue)(2)color(white)(000)10`
`color(white)(000000)"/"color(white)(00)"\"`
`color(white)(00000)color(blue)(2)color(white)(0000)color(blue)(5)`