# Sieve — Prime factors Puzzle | Mathallery

Source: https://mathallery.com/games/sieve/

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# Sieve

Prime factors · 30 levels

Divide whole rows and columns until every tile is 1.

## How to play

- Pick a prime key (÷2, ÷3, ÷5, ÷7), then tap a row or column arrow.
- Every tile in that line that divides evenly by the key is divided by it. The others stay the same.
- Turn every tile into 1. Each key has only a few uses, so choose your lines wisely!

Key selection stays active when tapped again. When a key runs out, the next available prime is selected automatically. Break each number into primes first: 12 = 2 × 2 × 3 needs two ÷2s and one ÷3 through its row or column.

[Open Sieve](https://mathallery.com/#/play/sieve/1)

Teeter, Tint and Echo Heist are free starters. Other games unlock through earned game choices or permanent packs. Your progress stays in the browser; optional sign-in saves it to your website account.