Find the prime factorization of the number 315.

Step 1 ：First, let's start by finding the smallest prime number that divides 315. We find that it is 3. We divide 315 by 3 to get 105.

Step 2 ：Next, we continue the process with the quotient we got. The smallest prime number that divides 105 is 5. We divide 105 by 5 to get 21.

Step 3 ：Finally, we continue with the quotient of 21. The smallest prime number that divides 21 is 3. We divide 21 by 3 to get 7, which is itself a prime number. This means we have completed the prime factorization.