What is a factor?

A factor of a number is a whole number that divides into it with no remainder. Every number has 1 and itself as factors; numbers with exactly two factors are prime.

Examples

• Factors of 12: 1, 2, 3, 4, 6, 12.
• 3 is a factor of 15 because 15 ÷ 3 = 5.
• 7 is prime , factors are just 1 and 7.

Quick facts

• Factors come in pairs (e.g. 2 and 6 for 12).
• The largest factor two numbers share is the GCF.