There are 792 different ways of choosing 5 books from a shelf containing 12 books. This problem can be solved using the combination formula of mathematics. The combination formula of mathematics is a number of way of selecting thing from a collection and the formula stated as n(n-1)...(n-k+1)/k(k-1)...1 (Calculation: 12*11*10*9*8/5*4*3*2*1 = 95040/120 = 792).