The Sieve of Eratosthenes Worksheet with Answer Key

What's on the worksheet

1. Decide if each number is prime, composite or neither, and factor the composites.
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2. Word problem: the fewest rows for the 203 students in the class photo.
3. Use the 1 to 100 grid to see which columns still hold numbers after the rounds for 2 and 5.
4. Explain why none of the first four primes divides 2 × 3 × 5 × 7 + 1.
5. Find the smallest board and the rounds needed when a sieve uses only certain primes.