The factors of 100 are the whole numbers that divide 100 exactly, leaving no remainder: 1, 2, 4, 5, 10, 20, 25, 50, 100. Use the calculator above for any number, or read on for the factor pairs, prime factorization and properties of 100.
What are the factors of 100?
A factor of 100 is any whole number that divides 100 with no remainder. Listing them from smallest to largest, the factors of 100 are:
1, 2, 4, 5, 10, 20, 25, 50, 100
So 100 is a composite number with 9 factors in total. Every number has 1 and itself as factors; the interesting work is finding the ones in between.
Factor pairs of 100
A factor pair is two numbers that multiply to give 100. The factor pairs of 100 are:
| Factor pair | Product |
|---|---|
| 1 × 100 | 100 |
| 2 × 50 | 100 |
| 4 × 25 | 100 |
| 5 × 20 | 100 |
| 10 × 10 | 100 |
Prime factorization of 100
The prime factorization breaks 100 down into a product of prime numbers only:
$$ 100 = 2^{2} \times 5^{2} $$How to find the factors of 100, step by step
- Start at 1 — 1 divides every number, so 1 and 100 are always factors.
- Test each whole number from 2 upward: if it divides 100 exactly, it is a factor.
- Use factor pairs — each small factor gives a matching large factor, so you only need to test up to $\sqrt{100}$.
- List them in order to get all 9 factors of 100.
Factors versus multiples of 100
It is easy to mix these up. The factors of 100 are the numbers that divide into 100 (they are less than or equal to 100), while the multiples of 100 are what you get by multiplying 100 outward: 100, 200, 300, 400, and so on. In short: factors go in, multiples go out. 100 is an even number, and its smallest prime factor is 2.
Properties of 100
| Number of factors | 9 |
| Sum of factors | 217 |
| Sum of proper divisors | 117 |
| Prime or composite | Composite |
| Even or odd | Even |
| Perfect square | Yes |
| Prime factorization | 2^2 x 5^2 |
Is 100 abundant, deficient or perfect?
Number theorists classify a number by comparing it to the sum of its proper divisors (all its factors except itself). For 100, those proper divisors add up to 117, which makes 100 an abundant number (its proper divisors sum to 117, which is more than 100). Most numbers are deficient; abundant and perfect numbers are comparatively rare, which is what makes this property interesting.
Using the factors of 100 for GCF and LCM
The prime factorization $2^{2} \times 5^{2}$ is the shortcut for combining 100 with another number. To find the greatest common factor (GCF), take the primes 100 shares with the other number, each to the lowest power. For the least common multiple (LCM), take every prime that appears in either number, each to the highest power. This is why the prime factorization is worth writing down — it does the heavy lifting for fractions, ratios and simplification.
Related factors and tools
Explore more: Factors of 98 Factors of 96 Factors of 108. Or find the factors of any number with the Factor Calculator. Exponents are the reverse idea — see logarithms and read the formal reference on divisors at Wikipedia.