Let's start with the smallest prime number 2
60/2 = 30
Divide that result over 2
30/2 = 15
We can't divide this by 2 because 15/2 = 7.5 isn't a whole number
Let's move onto 3
15/3 = 5
The result is a prime number, so we stop.
The values we divided as denominators were: {2, 2, 3}
We add the result 5 to the set to completely list all of the prime factors of 60
The prime factorization would be
60 = 2*2*3*5
which is the same as saying
60 = 2^2*3*5