The sieve of Eratosthenes is a simple, ancient algorithm for finding all prime numbers up to any given limit.

Application of the sieve of Eratosthenes to determine all prime numbers less than or equal to 50.

In what follows we will understand the algorithm. But before starting, we need to understand well the notions of multiple, divisor, and prime number. In case you already master these concepts, click here.

Atractor made an effort to make these pages readable by Lower Secondary students. Any suggestion that might help to improve this goal is welcome.

This work integrates interactive components in CDF format prepared with the Mathematica program. To use these files, you must download them to your computer and access them with the CDF Player, which can be downloaded for free from

(*) This work was carried out under a grant by FCT - Fundação para a Ciência e a Tecnologia.

Difficulty level: Lower Secondary