数学题求教

Q4:

If xy = 165, where x and y
are positive integers and x > y, what is the least possible
value of x – y ?

A.      2

B.       4

C.       8

D.    15

E.     28

165=5*3*11

possible x and y:55,3;33,5;15,11

so x-y=15-11=4 B is the right answer