Quantitative Aptitude • Number System & SimplificationEasy
What is the HCF (highest common factor) of 90 and 165?
A. 5
B. 45
C. 15✓ Correct Answer
D. 30
💡 Solution & Explanation
Write both numbers using a common factor: 90 = 15 × 6 and 165 = 15 × 11. The numbers 6 and 11 have no common factor other than 1, so nothing larger than 15 divides both. Therefore the HCF of 90 and 165 is 15. A quick check: the HCF must also divide the difference of the two numbers, and 75 ÷ 15 = 5.
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