1. What is the HCF of 12 and 18?
- A6
- B3
- C9
- D36
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Answer: A) 6
Factors of 12: 1,2,3,4,6,12. Factors of 18: 1,2,3,6,9,18. Common factors: 1,2,3,6. The highest is 6.
Class 6 HCF and LCM — practice questions with answers
Playing with Numbers · 5 sample questions from the school syllabus. Try each one, then open the answer and the worked solution.
2. What is the LCM of 2, 3 and 4?
- A12
- B24
- C6
- D8
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Answer: A) 12
LCM of 2 and 3 is 6; LCM of 6 and 4 = 12 (since 12 is the smallest number divisible by 2,3,4).
3. What is the smallest number that is exactly divisible by both 6 and 9?
- A18
- B54
- C3
- D27
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Answer: A) 18
Smallest number divisible by both = LCM(6,9). 6 = 2x3, 9 = 3x3, LCM = 2x3x3 = 18.
4. A florist in Jaipur has 24 marigolds, 36 roses and 48 lilies.
She makes identical garlands using all flowers, each garland having the same number of each type of flower.
What is the greatest number of garlands she can make?
She makes identical garlands using all flowers, each garland having the same number of each type of flower.
What is the greatest number of garlands she can make?
- A12
- B13
- C11
- D24
Show answer
Answer: A) 12
Greatest number of equal garlands = HCF(24,36,48). 24=2³x3, 36=2²x3², 48=2⁴x3, HCF = 2²x3 = 12.
5. Three bells in a school ring at intervals of 9, 12 and 15 minutes.
They all ring together at 9:00 am.
How many times in the next 3 hours (from 9:00 am up to and including 12:00 noon) will they ring together again?
They all ring together at 9:00 am.
How many times in the next 3 hours (from 9:00 am up to and including 12:00 noon) will they ring together again?
- A1
- B2
- C3
- D4
Show answer
Answer: A) 1
They ring together every LCM(9,12,15) minutes. 9=3², 12=2²x3, 15=3x5, LCM = 2²x3²x5 = 180 minutes = 3 hours. In the next 3 hours they ring together once, exactly at 12:00 noon.
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