Quantitative Aptitude • Number System & SimplificationEasy
What is the HCF (highest common factor) of 36 and 99?
A. 3
B. 18
C. 9✓ Correct Answer
D. 27
💡 Solution & Explanation
Write both numbers using a common factor: 36 = 9 × 4 and 99 = 9 × 11. The numbers 4 and 11 have no common factor other than 1, so nothing larger than 9 divides both. Therefore the HCF of 36 and 99 is 9. A quick check: the HCF must also divide the difference of the two numbers, and 63 ÷ 9 = 7.