Prime and Composite Numbers

Prime and Composite Numbers

Author: Kerrie Meagher
  • I can ​explain whether a whole number is prime, composite or neither by finding the number of factors
  • I can ​explain why a prime number, when modelled as an array, can have only one row

An activity to find the factors of the numbers 1 - 12 and determine whether the numbers are prime or composite

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  • Write the KEY WORDS and their definitions into your notebook
  • Add your own examples
  • Complete Activity Sheet 1 - Factors of Numbers 1 to 12
  • Answer these questions in your notebook:
  1. ​What is the only even prime number?
  2. Why is 1 neither prime nor composite?
  3. Do all composite numbers have an even number of factors?


Factor: A whole number that divides evenly into another whole number.

Example: 3 and 4 are factors of 12 because 12 ÷ 3 = 4


Prime Number: A whole number that can only be divided evenly by 1 and itself (that is, it has only 2 factors).

Example: 5 is a prime number because it can only be divided evenly by 1 and 5


Composite Number: A whole number than can be divided evenly by more than 2 factors

Example: 10 is a composite number because it can be divided evenly by 1, 2, 5 and 10


Activity Sheet 1 - Factors of Numbers 1 to 12

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Source: Kerrie Meagher