What is the prime factorization of 20 and 60?

Answer 1

Let's do 20 first.
20 can be written as 4x5. Note that 5 is prime but 4 is not. So write 4 as 2x2.
The prime factorization of 20 is 2x2x5.
Now for 60, we have 3x20.
We can use what we just did and write the prime factorization of 60 as
2x2x3x5.