True for n^2 = 900
False for n^2 = 60: INSUFF
True for 2n = 60
False for 2n = 30: INSUFF
n must be an integer. So n could be 15,30,45,60......
But squares of odd values are not divisible by 30. So n is 30,60,90.....
Hence 30 is a factor of n.: SUFF
SAID BUSINESS SCHOOL, OXFORD - MBA CLASS OF 2008