1. Find all natural numbers 'k' such that k{+2}+ k is prime? 

2. Who was considered to be the most important mathematician of antiquity?


1. 1

Solution: k{+2}+ k = k(k+1) which is product of two consecutive numbers and so will only be composite except if k = 1. 

2. Archimedes for his phenomenal contributions towards many branches of mathematics.