What is Prime Number Calculator?
Determines primality of an integer by trial division up to square root of N, identifying primes with only 2 factors: 1 and itself.
How to Use This Calculator
- Enter an integer to evaluate.
- Discover whether it is prime or composite, along with surrounding primes.
The Mathematical Formula & Variables
Test divisibility by primes up to sqrt(N)
Step-by-Step Worked Example
Scenario: Test if 97 is prime.
- sqrt(97) ≈ 9.85.
- Test prime divisors <= 9: 2, 3, 5, 7.
- 97 is not divisible by 2, 3, 5, or 7. Therefore, 97 is prime.
Result: 97 is a Prime Number
Frequently Asked Questions
Why is 1 not considered a prime number?
By definition, a prime number has exactly two distinct positive divisors: 1 and itself. The number 1 has only one divisor.