Factors of 40
Every whole number that divides 40 exactly, the factor pairs, and how to find them yourself.
The answer
The factors of 40 are 1, 2, 4, 5, 8, 10, 20 and 40.
Factor pairs of 40
| Pair | Makes |
|---|---|
| 1 × 40 | 40 |
| 2 × 20 | 40 |
| 4 × 10 | 40 |
| 5 × 8 | 40 |
Prime factors of 40
- Prime factorisation
- 40 = 2 × 2 × 2 × 5 (2³ × 5)
- Reading index form
- A small raised number tells you how many times to use that factor. For example, 2³ means 2 × 2 × 2.
- Is 40 prime?
- No. It has 8 factors, not just 1 and 40.
- Is 40 a square number?
- No. 6 × 6 = 36 and 7 × 7 = 49, so 40 falls between two square numbers.
How to find the factors of 40
40 is even, so 2 is sure to be a factor. It ends in 0, so 5 is a factor. Work up from 1 to 6, and write down both numbers in every pair you find.
- 40 ÷ 1 = 40, so 1 × 40 is a pair.
- 40 ÷ 2 = 20, so 2 × 20 is a pair.
- 3 does not go into 40 exactly.
- 40 ÷ 4 = 10, so 4 × 10 is a pair.
- 40 ÷ 5 = 8, so 5 × 8 is a pair.
- 6 does not go into 40 exactly.
Stop at 7: 7 × 7 = 49, which is more than 40. The next pair you would find is 8 × 5, which is 5 × 8 turned round, so you already have every pair.
40 in the times tables
2 × 20 = 40, 4 × 10 = 40 and 5 × 8 = 40. Practise the 4 times table, 5 times table, 8 times table, 10 times table and 20 times table.
More numbers
Check whether 40 is prime.
Questions parents ask
What is the largest factor of 40, apart from 40 itself?
20. Divide 40 by its smallest factor above 1, which is 2: 40 ÷ 2 = 20.
What do the factors of 40 add up to?
90. Leaving out 40 itself, they add up to 50, which is more than 40, so 40 is called an abundant number.
Which number after 40 has the same number of factors?
42. Like 40, it has exactly 8 factors.
Continue your number practice
Explore the diagnostic for another set of practice questions.