Factors of 18
The factors of 18 are the numbers that divide it exactly. Finding factors is the first step in simplifying fractions and factoring expressions.
A composite carrying 6 factors — factors always arrive in mirrored pairs, so the count comes out even. The largest prime factor is 3: 18 = 3 × 6. Every factor together sums to 39 — the proper divisors (all factors but 18 itself) add to 21, which is more than 18 itself, an abundant number. Shared factors between two numbers are what the GCF calculator hunts — the pairing column above feeds that search directly.
| Factor | Pairing |
|---|---|
| 1 | 1 × 18 = 18 |
| 2 | 2 × 9 = 18 |
| 3 | 3 × 6 = 18 |
| 6 | 6 × 3 = 18 |
| 9 | 9 × 2 = 18 |
| 18 | 18 × 1 = 18 |
Frequently asked questions
What are the factors of 18?
The factors of 18 are 1, 2, 3, 6, 9, 18 — that is 6 factors in total.
How do you find factors of 18?
Test each number from 1 up to 18: if it divides 18 with no remainder, it is a factor. Pair test — every factor pairs with a cofactor, like 1 × 2 = 18.
Why do factors matter for simplifying fractions?
Simplification divides both top and bottom by their greatest common factor — so a shared factor between two numbers, like you can find in the tables above, makes the fraction smaller and cleaner.