Factors
Key notes:
In mathematics, a factor is a number that divides another number completely without leaving a remainder. Understanding factors is essential for various topics in math, including algebra and number theory.
Here’s a simple breakdown of the concept:
Definition of a Factor:
- A factor of a number is an integer that divides the number evenly.
- For example, 2 is a factor of 8 because 8 ÷ 2 = 4 with no remainder.
Finding Factors:
- To find factors, you can start by testing numbers from 1 up to the number itself to see which ones divide it evenly.
- Example: To find the factors of 12, test numbers 1, 2, 3, 4, 6, and 12:
- 12 ÷ 1 = 12 (Factor)
- 12 ÷ 2 = 6 (Factor)
- 12 ÷ 3 = 4 (Factor)
- 12 ÷ 4 = 3 (Factor)
- 12 ÷ 6 = 2 (Factor)
- 12 ÷ 12 = 1 (Factor)
- So, the factors of 12 are 1, 2, 3, 4, 6, and 12.

Prime Factors:
- Prime factors are factors that are prime numbers. For instance, the prime factors of 12 are 2 and 3, since 12 = 2 × 2 × 3.
Factor Pairs:
- Factor pairs are two numbers that multiply together to give the original number.
- For 12, the factor pairs are (1, 12), (2, 6), and (3, 4).
Greatest Common Factor (GCF):
- The GCF is the largest factor that two or more numbers share.
- For example, the GCF of 12 and 18 is 6.
Learn with an example
Which number is a factor of 9?
- 5
- 27
- 2
- 3
Divide all the numbers into 9, and see which one divides evenly.
9 ÷ 5 = 1 R4 | No | |
9 ÷ 27 = 0 R9 | No | |
9 ÷ 2 = 4 R1 | No | |
9 ÷ 3 = 3 R0 | Yes, 3 divides evenly |
3 divides evenly into 9, so 3 is a factor.
Which number is a factor of 16?
- 7
- 5
- 4
- 3
Divide all the numbers into 16, and see which one divides evenly.
16 ÷ 7 = 2 R2 | No | |
16 ÷ 5 = 3 R1 | No | |
16 ÷ 4 = 4 R0 | Yes, 4 divides evenly | |
16 ÷ 3 = 5 R1 | No |
4 divides evenly into 16, so 4 is a factor.
Which number is a factor of 10?
- 3
- 6
- 2
- 4
Divide all the numbers into 10, and see which one divides evenly.
10 ÷ 3 = 3 R1 | No | |
10 ÷ 6 = 1 R4 | No | |
10 ÷ 2 = 5 R0 | Yes, 2 divides evenly | |
10 ÷ 4 = 2 R2 | No |
2 divides evenly into 10, so 2 is a factor.
let’s practice!