Factors of 87
Every whole number that divides 87 exactly, the factor pairs, and how to find them yourself.
The answer
The factors of 87 are 1, 3, 29 and 87.
Factor pairs of 87
| Pair | Makes |
|---|---|
| 1 × 87 | 87 |
| 3 × 29 | 87 |
Prime factors of 87
- Prime factorisation
- 87 = 3 × 29
- Is 87 prime?
- No. It has 4 factors, not just 1 and 87.
- Is 87 a square number?
- No. 9 × 9 = 81 and 10 × 10 = 100, so 87 falls between two square numbers.
How to find the factors of 87
87 is odd, so every even number you try will fail. Its digits add up to 15, a multiple of 3, so 3 is a factor. Work up from 1 to 9, and write down both numbers in every pair you find.
- 87 ÷ 1 = 87, so 1 × 87 is a pair.
- 2 does not go into 87 exactly.
- 87 ÷ 3 = 29, so 3 × 29 is a pair.
- 4 does not go into 87 exactly.
- 5 does not go into 87 exactly.
- 6 does not go into 87 exactly.
- 7 does not go into 87 exactly.
- 8 does not go into 87 exactly.
- 9 does not go into 87 exactly.
Stop at 10: 10 × 10 = 100, which is more than 87. The next pair you would find is 29 × 3, which is 3 × 29 turned round, so you already have every pair.
More numbers
Check whether 87 is prime.
Questions parents ask
What is the largest factor of 87, apart from 87 itself?
29. Divide 87 by its smallest factor above 1, which is 3: 87 ÷ 3 = 29.
What do the factors of 87 add up to?
120. Leaving out 87 itself, they add up to 33, which is less than 87, so 87 is called a deficient number.
Which number after 87 has the same number of factors?
91. Like 87, it has exactly 4 factors.
Number facts are the base of 11+ maths
Factors, multiples, primes and square numbers come up all over 11+ maths, from simplifying fractions to ratio. The free diagnostic checks maths, English and both kinds of reasoning, and shows what to practise next. No card is required.