factor

Everyday

1. In maths, a factor is a whole number that divides exactly into another number with no remainder: 3 is a factor of 12. tree →
2. A factor is one of the things that causes or affects a result. tree →
3. To factor something in is to include it when you plan or work something out. tree →
4. A factor (such as sun protection factor) is a number showing how strong something is. tree →
5. A factor is an agent who buys, sells or looks after goods for someone else. tree →

In the lessons

In maths lessons, pupils list the factors of a number, find common factors, the highest common factor, and prime factors; factors come in pairs that multiply to the number. In everyday life, the weather can be a factor in a decision. On sun cream, «factor 50» shows the strength. Phrases: a factor of, common factor, prime factor, scale factor, key factor, factor in.

Examples

• The factors of 12 are 1, 2, 3, 4, 6 and 12. tree →
• 5 is not a factor of 12, because 12 ÷ 5 leaves a remainder. tree →
• The highest common factor of 8 and 12 is 4. tree →
• Rain was a big factor in the team losing. tree →
• Put on factor 50 sun cream at the beach. tree →
• Don't forget to factor in time for lunch. tree →
• Multiply each side by the scale factor 3 to make the shape bigger. tree →
• 2 and 3 are the prime factors of 6. tree →
• Away flew the factor, while another dinner was providing, and returned with the cat just as the rats and mice were devouring that also. tree →

Note

Do not confuse factors with multiples: factors of 12 are smaller numbers that go into 12; multiples of 12 are 12, 24, 36… Every number has 1 and itself as factors. A prime number has exactly two factors. A scale factor tells you how many times larger or smaller a shape becomes.