Finding prime factors

Prime factors are factors of a number that are, themselves, prime numbers.

Sometimes you might be asked to write a number as the product of its prime factors.

There are many methods to find the prime factors of a number, but one of the most common is to use a prime factor tree:

  • Start the factor tree using any pair of factors (two numbers that multiply together to make your number).
  • If one of these factors is prime, that branch ends.
  • If a factor isn't prime, divide it into a factor pair.
  • The branches continue to expand until all the factors are prime numbers.
  • The final answer is the list of all the prime numbers displayed at the end of these branches.

Note that the number \({1}\) is not used within a factor tree.


Write 24 as the product of its prime factors.

Factor tree diagram

Write 24 as the product of its prime factors

You could choose any factor pair to start.