4. When looking for the unique factorization of an integer, progress through the primes in a systematic order, checking for divisibility. Remember that a prime number might divide into your integer more than once. Start by checking if 2 divides into your integer. If it does, then check if 2 divides into your integer more than once. After you have factored out all the 2s, move on to 3, then 5, then 7 etc...