"How did the "" _ + _ + _ = 30 using 1, 3, 5, 7, 9, 11, 13 and 15"" riddle become so popular?"
If a set such that S= {1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20} then how many subset can be made where the product of elements will be even?