Factors of 16
Every whole number that divides 16 exactly, the factor pairs, and how to find them yourself.
The answer
The factors of 16 are 1, 2, 4, 8 and 16.
Factor pairs of 16
| Pair | Makes |
|---|---|
| 1 × 16 | 16 |
| 2 × 8 | 16 |
| 4 × 4 | 16 |
4 × 4 uses the same number twice, so 4 counts once. That is why 16 has an odd number of factors: 5.
Prime factors of 16
- Prime factorisation
- 16 = 2 × 2 × 2 × 2 (2⁴)
- Reading index form
- A small raised number tells you how many times to use that factor. For example, 2³ means 2 × 2 × 2.
- Is 16 prime?
- No. It has 5 factors, not just 1 and 16.
- Is 16 a square number?
- Yes. 4 × 4 = 16.
How to find the factors of 16
16 is even, so 2 is sure to be a factor. It is a square number, so one pair is 4 × 4, the same number twice. Work up from 1 to 4, and write down both numbers in every pair you find.
- 16 ÷ 1 = 16, so 1 × 16 is a pair.
- 16 ÷ 2 = 8, so 2 × 8 is a pair.
- 3 does not go into 16 exactly.
- 16 ÷ 4 = 4, so 4 × 4 is a pair.
Stop at 5: 5 × 5 = 25, which is more than 16. The next pair you would find is 8 × 2, which is 2 × 8 turned round, so you already have every pair.
16 in the times tables
2 × 8 = 16 and 4 × 4 = 16. Practise the 2 times table, 4 times table and 8 times table.
More numbers
Check whether 16 is prime or see the square root of 16.
Questions parents ask
What is the largest factor of 16, apart from 16 itself?
8. Divide 16 by its smallest factor above 1, which is 2: 16 ÷ 2 = 8.
What do the factors of 16 add up to?
31. Leaving out 16 itself, they add up to 15, which is less than 16, so 16 is called a deficient number.
Which number after 16 has the same number of factors?
81. Like 16, it has exactly 5 factors.
Continue your number practice
Explore the diagnostic for another set of practice questions.