If a*b denotes the greatest common divisor of a and b, then ((16*20)*(18*24)) = ? Pick
A) 24  B) 12  C) 6  D) 4  E) 2
The greatest common divisor of 16 and 20 is 4. Hence 16*20 = 4 (note that * here denotes the function not multiplication).   The greatest common divisor of 18 and 24 is 6. Hence 18*24 = 6.   Hence ((16*20)*(18*24)) = 4*6.   The greatest common divisor of 4 and 6 is 2.   Answer; 2.
<result>E</result>
If a*b denotes the greatest common divisor of a and b, then ((16*20)*(18*24)) = ?