Extensive LCM Practice Questions for Mastering Calculations

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Practice makes perfect, especially when learning about the Lowest Common Multiple (LCM). This page is packed with LCM practice questions to help you build speed and accuracy in your calculations. We've included a wide variety of number sets and word problems for comprehensive practice.

Try solving these questions yourself. If you get stuck finding the LCM or want to double-check your answer quickly, use our handy LCM Calculator Tool!

Check your final answers against the answer key provided at the bottom of this page.

LCM Practice Questions

Number Sets (Find the LCM):

  1. 14, 21
  2. 16, 20
  3. 9, 24
  4. 15, 18, 20
  5. 7, 13
  6. 30, 40, 50
  7. 12, 36
  8. 25, 35
  9. 8, 10, 12
  10. 18, 24, 32
  11. 11, 15
  12. 4, 6, 9
  13. 20, 28, 35
  14. 9, 16
  15. 50, 75
  16. 6, 11, 12
  17. 2, 3, 4, 5
  18. 10, 14, 35
  19. 27, 30
  20. 13, 26, 39

LCM Word Problems for Practice:

  1. Two lighthouses flash their lights at different intervals. One flashes every 15 seconds, and the other flashes every 18 seconds. If they flash together at midnight, after how many seconds will they next flash together?
  2. What is the smallest number of students that can be arranged in rows of 10, 12, or 15 with no students left over?
  3. Find the least number of square tiles required to pave the ceiling of a room whose length is 15 m 17 cm and breadth is 9 m 2 cm? (This is a classic HCF problem, often confused. Let's replace it with a clear LCM one) -> **Revised 23:** Find the side length (in cm) of the smallest square that can be completely filled using rectangular cards of size 15 cm x 6 cm.
  4. Three friends are jogging on a circular track. They take 8 minutes, 10 minutes, and 12 minutes, respectively, to complete one lap. If they start at the same point at the same time, when will they meet again at the starting point?
  5. A red light flashes 3 times per minute and a green light flashes 5 times in two minutes. If they start flashing together, how many times will they flash together in one hour?
  6. Find the smallest number that leaves a remainder of 1 when divided by 2, 3, 4, and 5.
  7. Paper sheets are 12 inches long and 16 inches wide. What is the side length of the smallest square scrapbook page onto which these sheets can be tiled without any overlap or cutting?
  8. What is the capacity of the smallest container (in litres) that can be filled using jugs of capacity 3 litres, 4 litres, or 5 litres, using only full jugs each time?

Answer Key

Check your answers here. For detailed calculation steps, feel free to use our LCM Calculator linked above.

  1. 42
  2. 80
  3. 72
  4. 180
  5. 91
  6. 600
  7. 36
  8. 175
  9. 120
  10. 288
  11. 165
  12. 36
  13. 140
  14. 144
  15. 150
  16. 66
  17. 60
  18. 70
  19. 270
  20. 78
  21. 90 seconds
  22. 60 students
  23. 30 cm (LCM of 15 and 6)
  24. 120 minutes (or 2 hours)
  25. Calculation: Red flashes every 20 sec (60/3). Green flashes every 24 sec (120/5). LCM(20, 24) = 120 seconds (2 minutes). They flash together every 2 minutes. In one hour (60 mins), they flash together 60/2 = 30 times. (Note: This assumes they flash *together* at the start, which counts as the first time within the hour if the hour starts then). Let's refine: They flash together at 0, 2, 4,... 58 minutes. That's 30 times including the start. If the question means *after* the start, it's 29. Standard interpretation usually includes the start time within the period. Answer: 30 times.
  26. Find LCM(2, 3, 4, 5) = 60. The number is 60 + 1 = 61.
  27. LCM(12, 16) = 48. The side length is 48 inches.
  28. LCM(3, 4, 5) = 60. The smallest capacity is 60 litres.

Master LCM with Practice!

Consistent practice with these varied LCM practice questions is key to understanding the concept thoroughly. Remember to use our LCM Calculator Tool whenever you need assistance or want to verify your results quickly!

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