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Prime and composite numbers worksheets Grades 4–5

Decide whether each number is prime or composite.

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Free · Worked example · 57 problems · Answer key · US Letter

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How to do it

A prime has exactly two factors: 1 and itself. 1 is neither prime nor composite.

26: prime or composite?composite26:\ \text{prime or composite?}\quad \text{composite}
26=2×1326 = 2 \times 13more than two factors: composite

Example problems

  1. 89: prime or composite?89:\ \text{prime or composite?}
  2. 51: prime or composite?51:\ \text{prime or composite?}
  3. 11: prime or composite?11:\ \text{prime or composite?}
  4. 41: prime or composite?41:\ \text{prime or composite?}

Factors, multiples and prime numbers

  1. Divisibility rules
  2. Factor pairs
  3. Listing factors
  4. Prime and composite numbers
  5. Prime factorization
  6. Greatest common factor (GCF)
  7. Least common multiple (LCM)
  8. GCF and LCM mixed practice