To find the prime factorization, divide 
125
 by only prime numbers. Remember that prime numbers are whole numbers greater than 
1
 that are only evenly divisible by themselves and 
1
.
{
2
,
3
,
5
,
7
,
11
,
13
,
17
,
19
,
23
,
29
,
31
,
37
,
41
,
43
,
47
,
53
, etc.}
Since 
125
 ends in 
5
, it is evenly divisible by 
5
, which is a prime number. (How convenient!)
125
÷
5
=
25
25
 now has to be factored into its prime factors.
25
=
5
⋅
5
So, the prime factorization of 
125
 is
125
=
5
⋅
5
⋅
5
=
5
3