Quantitative Aptitude • Number System & SimplificationEasy
What is the HCF (highest common factor) of 126 and 147?
A. 21✓ Correct Answer
B. 42
C. 7
D. 63
💡 Solution & Explanation
Write both numbers using a common factor: 126 = 21 × 6 and 147 = 21 × 7. The numbers 6 and 7 have no common factor other than 1, so nothing larger than 21 divides both. Therefore the HCF of 126 and 147 is 21. A quick check: the HCF must also divide the difference of the two numbers, and 21 ÷ 21 = 1.