factor

A number which divides exactly into another number is known as a factor.

For example, 1, 2, 3, 4, 6 and 12 are all factors of 12.

–1, –2, –3, –4, –6 and –12 are also factors of 12, because multiplying two negative numbers gives a positive number.

In algebra, we can multiply factors together to get an expression.

For example, (x – 1) and (x + 4) are factors of x² + 3x – 4 because (x – 1) (x + 4) = x² + 3x – 4.