LCM Questions and Answers [Practice Sets with Answer Key]

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Are you searching for LCM questions and answers to test your knowledge of the Lowest Common Multiple? You're in the right place! This page provides numerous practice questions, neatly categorized, along with a straightforward answer key.

Solve the problems below to sharpen your skills. While we provide the final answers for checking, if you need help with the calculation steps or want a quick verification, please use our efficient LCM Calculator Tool.

LCM Practice Questions

Two Numbers (Find the LCM):

  1. 15, 21
  2. 18, 30
  3. 20, 25
  4. 8, 18
  5. 14, 35
  6. 24, 40
  7. 11, 13
  8. 28, 42
  9. 32, 48
  10. 5, 12
  11. 26, 65
  12. 40, 60

Three Numbers (Find the LCM):

  1. 10, 15, 20
  2. 6, 9, 15
  3. 4, 12, 18
  4. 7, 8, 9
  5. 16, 24, 30
  6. 5, 10, 11
  7. 14, 28, 35
  8. 9, 27, 36

Four Numbers (Find the LCM):

  1. 3, 6, 9, 12
  2. 2, 4, 6, 10
  3. 1, 2, 3, 7

LCM Word Problems:

  1. Find the smallest number which, when increased by 3, is exactly divisible by 10, 12, and 15.
  2. Three bells toll at intervals of 9, 12, and 15 minutes, respectively. If they start tolling together, after what time will they next toll together?
  3. Two cyclists start cycling from the same point at the same time around a circular path of 600m length. If they cycle at speeds of 6 m/s and 8 m/s respectively in the same direction, after how many seconds will they meet again at the starting point?
  4. What is the minimum number of oranges a fruit seller should have so that when he makes piles of 5, 6, or 7 oranges, no oranges are left over?
  5. Liam goes swimming every 6 days and hiking every 8 days. If he did both activities today, how many days will it be until he does both activities on the same day again?

Answer Key

Use this key to check your final answers. For calculation help, our LCM calculator is available via the link above.

  1. 105
  2. 90
  3. 100
  4. 72
  5. 70
  6. 120
  7. 91
  8. 84
  9. 96
  10. 60
  11. 130
  12. 120
  13. 60
  14. 90
  15. 36
  16. 504
  17. 240
  18. 110
  19. 140
  20. 108
  21. 36
  22. 60
  23. 42
  24. LCM(10, 12, 15) = 60. Number = 60 - 3 = 57.
  25. LCM(9, 12, 15) = 180. Time = 180 minutes (or 3 hours).
  26. Time = Distance / Speed. Time for cyclist 1 = 600/6 = 100s. Time for cyclist 2 = 600/8 = 75s. Find LCM(100, 75). LCM = 300 seconds.
  27. LCM(5, 6, 7) = 210 oranges.
  28. LCM(6, 8) = 24 days.

Find More Answers with Our Tool!

We hope these LCM questions and answers help your practice! Remember, understanding the concept is key, and our LCM Calculator Tool is always there to assist with the calculations.

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