Numbers and Quantities
Integers greater than 1 which are not prime are called composite numbers. All composite numbers can be written as a product of prime numbers. To find these prime numbers (factors), you do something called prime factorization. There are several methods for that. Here I’ll show you how to use a factor tree.
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Rule
Factor Trees
- 1.
- Find a product that has the number you want to factorize as the answer
(example: ).
- 2.
- Check if any of the factors are prime numbers. If you have a prime number, put a ring around it (3 is a prime number, put a ring around it).
- 3.
- If one or both of the numbers are not prime numbers, you need to find a product that is equal to the number(s) that are not prime numbers. (8 is not a prime number, you find the product ).
- 4.
- Check if any of these factors are prime numbers. If you have a prime number, put a ring around it (2 is a prime number, put a ring around it).
- 5.
- If one or both of the numbers are not prime numbers, you have to find a new product that equals the number(s) that are not prime numbers. (4 is not a prime number, you find the product ).
- 6.
- Check if any of the factors are prime numbers. If you have a prime number, put a ring around it. (2 is a prime number, put a ring around it).
- 7.
- Repeat the steps until all the arrows end in a number with a ring around it.
- 8.
- The numbers with rings around them are the prime factors of your number.
Example 1
Factor the number 24 into primes
24 is the product of all the prime numbers in the circles. That means you get
Example 2
Factor the number 100 into primes
100 is the product of all the prime numbers in the circles. That means you get
Example 3
Factor the number 144 into primes
144 is the product of all the prime numbers in the circles. Then you have
