Quantitative Aptitude • Number System & SimplificationEasy
What is the HCF (highest common factor) of 56 and 21?
A. 7✓ Correct Answer
B. 168
C. 14
D. 21
💡 Solution & Explanation
Write both numbers using a common factor: 56 = 7 × 8 and 21 = 7 × 3. The numbers 8 and 3 have no common factor other than 1, so nothing larger than 7 divides both. Therefore the HCF of 56 and 21 is 7. A quick check: the HCF must also divide the difference of the two numbers, and 35 ÷ 7 = 5.
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