Enter a range and we'll find the primes inside it, then draw random ones for you. Handy for math lessons, puzzles, and demonstrations.
Primes are the building blocks of the whole number system, and they turn up everywhere from cryptography to hashing to music theory. This tool lists every prime in your range and then picks random ones, which is useful for setting practice problems, generating quiz questions, or demonstrating how primes thin out as numbers grow.
Keep the range modest for teaching (say 1 to 100), or widen it to show how sparse primes become higher up. Turn off duplicates if you want a repeat to be possible.
Frequently asked questions
What is a prime number?
A whole number greater than 1 whose only divisors are 1 and itself — 2, 3, 5, 7, 11, and so on.
Is 1 a prime number?
No. By definition a prime has exactly two distinct divisors, and 1 has only one, so the tool starts from 2.
How large a range can I use?
Large ranges are fine, though very wide ranges take a moment longer while every prime inside them is found.