Railway Recruitment Board Mathematics — Question 1691
Question
The product of two numbers is 2028 and their HCF is 13. How many such pairs of numbers are possible?
- 1
- 3
- 4
- 2
Correct answer
D — 2
Explanation (English)
Let the numbers be 13a and 13b with a, b coprime. Product = 169ab = 2028, so ab = 12. Coprime pairs with product 12: (1,12) and (3,4). [(2,6) share factor 2.] Hence 2 pairs.
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