Ok, sorry, answered my own question..
http://www.utm.edu/research/primes/largest.html#intro
But I have another question:
Two sides of a right angled triangle measure 3cm and 4cm. What is the measure of the third side?
a) 5
b) 7
c) 12
d) cannot be determined
My ans is d because we dont know that the 3 and the 4 are the non-hypotenuse sides. But barron's has (a) as the answer. Is this a typo in my book?