JENECONKMaths Universe

Lowest Common Multiple (LCM)

Ages 9–13

Difficulty adapts to you

Lowest Common Multiple

The LCM of two or more numbers is the smallest number that is a multiple of all of them.

Your goals

  • ✓You can find the smallest number that is a multiple of two or more numbers.
  • ✓You can use common multiple, LCM correctly.
  • ✓You can confirm that every starting number divides your answer exactly.

Words to know

common multiple:
A number that is a multiple of each number being considered.
LCM:
The smallest positive common multiple.

Examples

  • 1Multiples of 4: 4, 8, 12, 16, 20... Multiples of 6: 6, 12, 18... LCM(4, 6) = 12
  • 2LCM(3, 5) = 15 (15 is the first number in both lists)

Check these

  • • Do not choose the first multiple listed for only one number.
  • • Keep every number, symbol, label, and unit in its correct place.
  • • Show enough working to check how you reached your answer.

Helpful habits

  • • Read the whole question before choosing what to do.
  • • Show one clear step at a time and check each step.
  • • If you are stuck, draw a model, try smaller numbers, or revisit the example.

Now try your own

Create your own lowest common multiple (lcm) example, solve it, and explain how you checked it.

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Helpful Hints

“Hint: Break big problems into smaller steps!”