Printable Least Common Multiple Worksheets

Least common multiple worksheets teach 4th and 5th graders to find the smallest shared multiple of two numbers. These printable sheets build common denominator foundations with full answer keys.

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Structured, printable skill sheets with step-by-step guidance for Least Common Multiple.

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About Least Common Multiple

What this skill is

The Least Common Multiple (LCM) is the smallest positive whole number that is a multiple of two or more given numbers, used to find common denominators when adding or subtracting fractions.

When children learn it

Introduced in 4th and 5th grade to support fraction addition and subtraction (CCSS 5.NF.A.1) and finalized in 6th grade.

Teaching Tips

  • Start with the BIGGER number: for 4 and 6, write multiples of 6 (6, 12, 18...). Test each one with 4: Does 4 go into 6? No. Does 4 go into 12? Yes! Stop right there, 12 is your LCM.

Common Mistakes

  • Simply multiplying the two numbers together instead of finding the true least common multiple (e.g., using 24 for 4 and 6 instead of 12).
  • Confusing LCM with GCF and giving a smaller factor.
  • Calculation slips when skip counting large numbers.