Arithmetic Grade Four

Lesson Sixty-six: Factoring

What are all the different ways we can multiply two numbers to get 12? 

     1 x 12 = 12
     2 x  6 = 12
     3 x  4 = 12
This set of numbers (1, 2, 3, 4, 6, 12) are the factors of 12.

What are all the different ways we can multiply to numbers to get 20? 


     1 x 20 = 20
     2 x 10 = 20
     4 x  5 = 20
This set of numbers (1, 2, 4, 5, 10, 20) are the factors of 20.

Which of the following is not a factor of 15?

  1. 3
  2. 5
  3. 4
  4. 15
The correct answer is 4. We can multiply 3 x 5 to get 15 which makes answers a and b factors of 15 and of course 15 is a factor of 15 since we can multiply it by 1 to get 15.

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