Quantitative Aptitude • Number System & SimplificationEasy
What is the HCF (highest common factor) of 20 and 25?
A. 15
B. 100
C. 5✓ Correct Answer
D. 10
💡 Solution & Explanation
Write both numbers using a common factor: 20 = 5 × 4 and 25 = 5 × 5. The numbers 4 and 5 have no common factor other than 1, so nothing larger than 5 divides both. Therefore the HCF of 20 and 25 is 5. A quick check: the HCF must also divide the difference of the two numbers, and 5 ÷ 5 = 1.
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