Sieve of Eratosthenes

Visualize the primes up to n

Cross out the multiples of each prime, starting from 2 — every number left unmarked is prime.
Primes up to n — π(n)
10
Largest prime ≤ n
29
Sum of primes
129
Composite numbers
19
Prime density
33,33%
Prime numbers
2357111317192329
Sieve of EratosthenesNumber grid from 1 to 30: the 10 prime numbers are highlighted and the composite numbers are dimmed.123456789101112131415161718192021222324252627282930