Answer:
2 x 2 x 5 x 5
Explanation:
since 2, 3, and 5 are prime numbers I always begin by seeing if the number to be factored has those as factors
100 is divisible by 2 so you can start there:
2 x 50
50 is divisible by 2 so you now have:
2 x 2 x 25
25 is divisible by 5 so you now have all prime factors whose product is 100
2 x 2 x 5 x 5