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File:Sieve of Eratosthenes animation.gif

Sieve_of_Eratosthenes_animation.gif ‎(445 × 369 pixels, file size: 154 KB, MIME type: image/gif, looped, 159 frames, 37 s)
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Summary

Animation that visualizes the "Sieve of Eratosthenes" algorithm. Original image at Image:Animation_Sieve_of_Eratosth.gif Original by SKopp (selfmade)

The Sieve of Eratosthenes is an method for efficiently finding all prime numbers up to a number, 120 in this case, by eliminating (colouring in) all multiples of successive primes. It uses the common optimisation of starting at p2 for each prime p, as all non-primes (composites) up to p2 were found in previous passes. Because of this it needs only consider primes up to 7, because the square of the next prime 11 is 121, larger than any number here.

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