LCM Practice Quiz: The Ultimate LCM Practice Quiz – Concepts, Problems & Applications

  • 6th Grade
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| Questions: 20 | Updated: Dec 17, 2025
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1) What is the LCM of 3 and 5?

Explanation

Prime factors: 3=3, 5=5. LCM = 3×5 = 15.

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About This Quiz
LCM Practice Quiz: The Ultimate LCM Practice Quiz Concepts, Problems & Applications - Quiz

How do you determine the least common multiple efficiently and accurately? In this quiz, you’ll practice finding LCMs using prime factorization, multiples lists, and structured comparisons. You’ll analyze number pairs and sets, explore real uses of LCM in timing and repetition problems, and recognize when the method matters. As you... see morework through examples, you’ll develop a stronger grasp of how common multiples behave and how to choose the quickest strategy for each problem.
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2) What is the LCM of 7 and 3?

Explanation

Prime factors: 7=7, 3=3. LCM = 7×3 = 21.

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3) What is the LCM of 4 and 6?

Explanation

Prime factors: 4=2², 6=2×3. LCM = 2²×3 = 12.

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4) What is the LCM of 9 and 12?

Explanation

9=3², 12=2²×3. LCM = 2²×3² = 36.

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5) What is the LCM of 8 and 14?

Explanation

8=2³, 14=2×7. LCM = 2³×7 = 56.

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6) Find the LCM of 2 and 9: ____

Explanation

2=2, 9=3² → LCM = 2×3² = 18.

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7) A school bell rings every 10 minutes and another every 15 minutes. After how many minutes will both ring together?

Explanation

LCM(10,15): 10=2×5, 15=3×5 → LCM = 2×3×5 = 30.

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8) A light changes every 8 seconds, another every 12 seconds. When will they both change at the same time?

Explanation

LCM(8,12): 8=2³, 12=2²×3 → LCM = 2³×3 = 24.

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9) A gardener plants tulips in rows of 6 and daffodils in rows of 8. How many flowers fit evenly in each row?

Explanation

LCM(6,8): 6=2×3, 8=2³ → LCM = 2³×3 = 24.

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10) Two buses run every 28 and 42 minutes. When will both arrive together?

Explanation

28=2²×7, 42=2×3×7 → LCM = 2²×3×7 = 84.

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11) A projector changes reels every 12 and 16 minutes. Both change together every ____ minutes.

Explanation

12=2²×3, 16=2⁴ → LCM = 2⁴×3 = 48.

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12) A baker bakes croissants every 6 hours and pies every 9 hours. After how many hours will both be baked together?

Explanation

LCM(6,9): 6=2×3, 9=3² → LCM = 2×3² = 18.

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13) A runner takes water breaks every 14 and 21 minutes. When will they both stop together?

Explanation

14=2×7, 21=3×7 → LCM = 2×3×7 = 42.

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14) Find the LCM of 20 and 28.

Explanation

20=2²×5, 28=2²×7 → LCM = 2²×5×7 = 140.

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15) Find the LCM of 16 and 18.

Explanation

16=2⁴, 18=2×3² → LCM = 2⁴×3² = 144.

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16) Find the LCM of 22 and 44.

Explanation

22=2×11, 44=2²×11 → LCM = 2²×11 = 44.

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17) Find the LCM of 45 and 60.

Explanation

45=3²×5, 60=2²×3×5 → LCM = 2²×3²×5 = 180.

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18) Find the LCM of 36 and 54.

Explanation

36=2²×3², 54=2×3³ → LCM = 2²×3³ = 108.

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19) The LCM of two prime numbers is always their product.

Explanation

For primes p and q, they share no factors. So LCM(p,q) = p×q.

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20) Find LCM of 25 and 40: ____

Explanation

25=5², 40=2³×5 → LCM = 2³×5² = 200.

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What is the LCM of 3 and 5?
What is the LCM of 7 and 3?
What is the LCM of 4 and 6?
What is the LCM of 9 and 12?
What is the LCM of 8 and 14?
Find the LCM of 2 and 9: ____
A school bell rings every 10 minutes and another every 15 minutes....
A light changes every 8 seconds, another every 12 seconds. When will...
A gardener plants tulips in rows of 6 and daffodils in rows of 8. How...
Two buses run every 28 and 42 minutes. When will both arrive together?
A projector changes reels every 12 and 16 minutes. Both change...
A baker bakes croissants every 6 hours and pies every 9 hours. After...
A runner takes water breaks every 14 and 21 minutes. When will they...
Find the LCM of 20 and 28.
Find the LCM of 16 and 18.
Find the LCM of 22 and 44.
Find the LCM of 45 and 60.
Find the LCM of 36 and 54.
The LCM of two prime numbers is always their product.
Find LCM of 25 and 40: ____
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