The product of two numbers is 2028 and their H.C.F. is 13. The number of such pairs is:  Choose the correct choice from the following:
A) 1	B) 2	C) 3	D) 4	E) 5
EXPLANATION   Let the numbers 13a and 13b.   Then, 13a x 13b = 2028   ab = 12.   Now, the co-primes with product 12 are (1, 12) and (3, 4).   [Note: Two integers a and b are said to be coprime or relatively prime if they have no common positive factor other than 1 or, equivalently, if their greatest common divisor is 1 ]   So, the required numbers are (13 x 1, 13 x 12) and (13 x 3, 13 x 4).   Clearly, there are 2 such pairs.   Answer 2
<result>B</result>
The product of two numbers is 2028 and their H.C.F. is 13. The number of such pairs is: