Factors of 99
Every whole number that divides 99 exactly, the factor pairs, and how to find them yourself.
The answer
The factors of 99 are 1, 3, 9, 11, 33 and 99.
Factor pairs of 99
| Pair | Makes |
|---|---|
| 1 × 99 | 99 |
| 3 × 33 | 99 |
| 9 × 11 | 99 |
Prime factors of 99
- Prime factorisation
- 99 = 3 × 3 × 11 (3² × 11)
- Reading index form
- A small raised number tells you how many times to use that factor. For example, 2³ means 2 × 2 × 2.
- Is 99 prime?
- No. It has 6 factors, not just 1 and 99.
- Is 99 a square number?
- No. 9 × 9 = 81 and 10 × 10 = 100, so 99 falls between two square numbers.
How to find the factors of 99
99 is odd, so every even number you try will fail. Its digits add up to 18, a multiple of 9, so 3 and 9 are factors. Work up from 1 to 9, and write down both numbers in every pair you find.
- 99 ÷ 1 = 99, so 1 × 99 is a pair.
- 2 does not go into 99 exactly.
- 99 ÷ 3 = 33, so 3 × 33 is a pair.
- 4 does not go into 99 exactly.
- 5 does not go into 99 exactly.
- 6 does not go into 99 exactly.
- 7 does not go into 99 exactly.
- 8 does not go into 99 exactly.
- 99 ÷ 9 = 11, so 9 × 11 is a pair.
Stop at 10: 10 × 10 = 100, which is more than 99. The next pair you would find is 11 × 9, which is 9 × 11 turned round, so you already have every pair.
99 in the times tables
9 × 11 = 99. Practise the 9 times table and 11 times table.
More numbers
Check whether 99 is prime.
Questions parents ask
What is the largest factor of 99, apart from 99 itself?
33. Divide 99 by its smallest factor above 1, which is 3: 99 ÷ 3 = 33.
What do the factors of 99 add up to?
156. Leaving out 99 itself, they add up to 57, which is less than 99, so 99 is called a deficient number.
Which number after 99 has the same number of factors?
116. Like 99, it has exactly 6 factors.
Continue your number practice
Explore the diagnostic for another set of practice questions.