by saurav.raaj Sun Mar 08, 2009 5:20 pm
to find whether X is divisible by 36, X must be divisible by 4 and 9 (or infact 2 x 2 x 3 x 3, i.e. two 2's AND two 3's)
if X is divisible by 12, that means X = k1 x 12 = k1 x 2 x 2 x 3, we are still missing a 3 here. Not Sufficient.
(k1 is the other integer factor)
if X is divisible by 9, that means X = k2 x 9 = k2 x 3 x 3, we are still missing a 4 (or 2x 2) here. Not Sufficient.
(k2 is the other integer factor)
if we combine both, then we get get X divisible by 12 and 9 which means X = k3 x (12 ~ 2 x 2 x 3) x (9 ~ 3 x 3)
(k3 is the other integer factor)
we can re-write this:
X = k3 x (12 ~ 2 x 2 x 3) x (9 ~ 3 x 3)
as
X = k3 x 12 x 9 = k3 x 4 x 3 x 3 x 3 = k3 x 36 x 3
So we see, 36 emerges as one of the factors, while k3 x 3 is the other.