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 be 13a and 13b.   Then, 13a * 13b = 2028   =&gt; ab = 12. Now, co-primes with product 12 are (1, 12) and (3, 4).   So, the required numbers are (13 * 1, 13 * 12) and (13 * 3, 13 * 4).   Clearly, there are 2 such pairs.   ANSWER IS 2
<result>B</result>
The product of two numbers is 2028 and their H.C.F. is 13. The number of such pairs is :