📐 Ages 8–12
Prime Number Sieve
Discover all primes up to 100 using the Sieve of Eratosthenes
Primes found: 0
Click "Next Step" to start the sieve!
Primes found so far:
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Sieve Complete!
You found all prime numbers up to 100.
💡 How the Sieve of Eratosthenes Works
The Sieve of Eratosthenes is an ancient algorithm for finding all prime numbers up to a given limit. Start with all numbers from 2 to 100. The first number (2) is prime — cross out all its multiples. Move to the next uncrossed number (3) — it's prime too — cross out its multiples. Repeat until no multiples remain. Every uncrossed number is prime!
■ Amber = current prime ■ Green = confirmed prime ■ Grey = composite