The HCF and the LCM of two numbers are 12 and 20 respectively. If one of the…
2024
The HCF and the LCM of two numbers are 12 and 20 respectively. If one of the numbers is 6, calculate the second number.
- A.
40
- B.
64
- C.
54
- D.
69
Attempted by 172 students.
Show answer & explanation
Correct answer: A
Solution:
Key formula: (first number) × (second number) = HCF × LCM
Compute HCF × LCM = 12 × 20 = 240.
Find the second number by dividing this product by the given number: 240 ÷ 6 = 40.
Therefore the computed second number is 40.
Check consistency: gcd(6, 40) = 2, which is not 12. That means the given HCF = 12 is inconsistent with one number being 6. The product formula gives 40, but the original HCF value cannot be correct for the pair (6, 40).