Hi binaras,

This question is really about 'mapping out' the information and not about 'doing math'

We're told that f(x) = (f(x-2))(f(x-1))(x) for x>0

So when the question asks for the f(50), we can map that out...

f(50) = (f(48) x (f(49) x 50

Unfortunately, that calculation requires that we deal with f(48) and f(49), but we can write down what those mean too:

f(48) = (f(46) x (f(47) x 48
f(49) = (f(47) x (f(48) x 49

Now, each of THOSE calculations would have two more calculations. This pattern would go on and on UNTIL we got to the other piece of information that we've been given:

f(x) = 1 for all x<1

This tells us that eventually, all of the calculations would end up getting multiplied by 1.

So, we'd have a GIGANTIC string of integers multiplied together (and it's all of the integers from 1 to 50, inclusive, with some duplicates). The question asks for the largest PRIME number that divides into that calculation. The largest prime that is between 1 and 50, inclusive is 47.

GMAT assassins aren't born, they're made,
Rich