Factors of 85
Every whole number that divides 85 exactly, the factor pairs, and how to find them yourself.
The answer
The factors of 85 are 1, 5, 17 and 85.
Factor pairs of 85
| Pair | Makes |
|---|---|
| 1 × 85 | 85 |
| 5 × 17 | 85 |
Prime factors of 85
- Prime factorisation
- 85 = 5 × 17
- Is 85 prime?
- No. It has 4 factors, not just 1 and 85.
- Is 85 a square number?
- No. 9 × 9 = 81 and 10 × 10 = 100, so 85 falls between two square numbers.
How to find the factors of 85
85 is odd, so every even number you try will fail. It ends in 5, so 5 is a factor. Work up from 1 to 9, and write down both numbers in every pair you find.
- 85 ÷ 1 = 85, so 1 × 85 is a pair.
- 2 does not go into 85 exactly.
- 3 does not go into 85 exactly.
- 4 does not go into 85 exactly.
- 85 ÷ 5 = 17, so 5 × 17 is a pair.
- 6 does not go into 85 exactly.
- 7 does not go into 85 exactly.
- 8 does not go into 85 exactly.
- 9 does not go into 85 exactly.
Stop at 10: 10 × 10 = 100, which is more than 85. The next pair you would find is 17 × 5, which is 5 × 17 turned round, so you already have every pair.
85 in the times tables
5 × 17 = 85. Practise the 17 times table.
More numbers
Check whether 85 is prime.
Questions parents ask
What is the largest factor of 85, apart from 85 itself?
17. Divide 85 by its smallest factor above 1, which is 5: 85 ÷ 5 = 17.
What do the factors of 85 add up to?
108. Leaving out 85 itself, they add up to 23, which is less than 85, so 85 is called a deficient number.
Which number after 85 has the same number of factors?
86. Like 85, it has exactly 4 factors.
Number facts are the base of 11+ maths
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