Prime Numbers 1 to 100
There are 25 prime numbers between 1 and 100: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97. A prime number is a whole number greater than 1 with exactly two factors — 1 and itself.
The 25 prime numbers from 1 to 100
| Range | Primes |
|---|---|
| 1–10 | 2, 3, 5, 7 |
| 11–20 | 11, 13, 17, 19 |
| 21–40 | 23, 29, 31, 37 |
| 41–60 | 41, 43, 47, 53, 59 |
| 61–80 | 61, 67, 71, 73, 79 |
| 81–100 | 83, 89, 97 |
What makes a number prime?
A prime number has exactly two distinct factors: 1 and the number itself. 7 is prime because nothing except 1 and 7 divides it evenly. 8 is not prime, because 2 and 4 also divide it.
1 is not a prime number — it has only one factor. 2 is the only even prime, since every other even number is divisible by 2.
Finding primes with the Sieve of Eratosthenes
Write the numbers 2 to 100. Circle 2, then cross out every multiple of 2. Move to the next uncrossed number (3), circle it, cross out its multiples, and repeat. Whatever remains circled is prime. It is exactly how the list above is produced.
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Frequently asked questions
There are 25 prime numbers between 1 and 100.
No. A prime must have exactly two factors, and 1 has only one factor (itself), so it is neither prime nor composite.
2 is the smallest prime number, and the only even one.