The prime factorization of 99 is 3 times 3 times 11, or 3^2 times 11. Prime factorization requires finding the prime numbers that multiply together to make a particular number. Prime numbers are numbers that are evenly divisible by only themselves and one.

To learn the prime factors of 99, find two numbers that multiply together to make 99, such as 9 and 11. Eleven is a prime factor because it is only divisible by itself and 1, but 9 is not prime. Next, find two numbers that multiply together to make 9, such as 3 times 3. Since 3 is prime, all the prime factors have been found.