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G.1 Identify factors

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What are factors?

Factors are numbers that are multiplied together to make another number. A factor divides a number evenly, leaving no remainder.

Examples:
  • 2 × 6 = 12 → both 2 and 6 are factors of 12
  • 3 × 5 = 15 → both 3 and 5 are factors of 15
  • 1 × 8 = 8 → both 1 and 8 are factors of 8
Note

Every number has at least two factors: 1 and itself.

How to identify factors

To identify the factors of a number, find all the whole numbers that divide it evenly with no remainder.

Steps:
  • Start with 1 and the number itself.
  • Test each whole number between them to see if it divides evenly.
  • If it divides evenly, both numbers in the multiplication are factors.
Note

You can check divisibility by using simple rules (for example, numbers ending in 0 or 5 are divisible by 5).

Example: Finding factors of 24

Let’s find all the factors of 24 by testing which numbers divide evenly into it.

Work through the example:
  • 1 × 24 = 24 → factors: 1, 24
  • 2 × 12 = 24 → factors: 2, 12
  • 3 × 8 = 24 → factors: 3, 8
  • 4 × 6 = 24 → factors: 4, 6
Note

The factors of 24 are 1, 2, 3, 4, 6, 8, 12, and 24. Always list factors in order from least to greatest.

Prime and composite numbers

A number with only two factors, 1 and itself, is a prime number. A number with more than two factors is a composite number.

Examples:
  • 7 → factors: 1, 7 → prime number
  • 9 → factors: 1, 3, 9 → composite number
  • 13 → factors: 1, 13 → prime number
Note

The number 1 is neither prime nor composite because it has only one factor—1 itself.

Why factors are important

Understanding factors helps you simplify fractions, find common denominators, and solve multiplication and division problems efficiently.

Example:
  • To simplify 12⁄18, use common factors (both share a factor of 6) → 12 ÷ 6 = 2, 18 ÷ 6 = 3, so 12⁄18 = 2⁄3.
Note

Knowing factors supports later math topics like fractions, ratios, and algebraic expressions.