Factors of 28
Every whole number that divides 28 exactly, the factor pairs, and how to find them yourself.
The answer
The factors of 28 are 1, 2, 4, 7, 14 and 28.
Factor pairs of 28
| Pair | Makes |
|---|---|
| 1 × 28 | 28 |
| 2 × 14 | 28 |
| 4 × 7 | 28 |
Prime factors of 28
- Prime factorisation
- 28 = 2 × 2 × 7 (2² × 7)
- Reading index form
- A small raised number tells you how many times to use that factor. For example, 2³ means 2 × 2 × 2.
- Is 28 prime?
- No. It has 6 factors, not just 1 and 28.
- Is 28 a square number?
- No. 5 × 5 = 25 and 6 × 6 = 36, so 28 falls between two square numbers.
How to find the factors of 28
28 is even, so 2 is sure to be a factor. Work up from 1 to 5, and write down both numbers in every pair you find.
- 28 ÷ 1 = 28, so 1 × 28 is a pair.
- 28 ÷ 2 = 14, so 2 × 14 is a pair.
- 3 does not go into 28 exactly.
- 28 ÷ 4 = 7, so 4 × 7 is a pair.
- 5 does not go into 28 exactly.
Stop at 6: 6 × 6 = 36, which is more than 28. The next pair you would find is 7 × 4, which is 4 × 7 turned round, so you already have every pair.
28 in the times tables
2 × 14 = 28 and 4 × 7 = 28. Practise the 4 times table, 7 times table and 14 times table.
More numbers
Check whether 28 is prime.
Questions parents ask
What is the largest factor of 28, apart from 28 itself?
14. Divide 28 by its smallest factor above 1, which is 2: 28 ÷ 2 = 14.
What do the factors of 28 add up to?
56. Leaving out 28 itself, they add up to 28, which is exactly 28, so 28 is a perfect number, one of only two below 100 (the other is 6).
Which number after 28 has the same number of factors?
32. Like 28, it has exactly 6 factors.
Continue your number practice
Explore the diagnostic for another set of practice questions.