1 billion is=1,000,000,000
count the zeros since it has only 10's as the factors
9 zeros
the 10=2 times 5
so there are 10 2's and 10 5's so the prime factorization is
2 times 2 times 2 times 2 times 2 times 2 times 2 times 2 times 2 times 2 times 5 times 5 times 5 times 5 times 5 times 5 times 5 times 5 times 5 times 5 or
2^10 times 5^10