1/2 - 1/3 = 3/6 - 2/6 = 1/6 1/3 - 1/4 = 4/12 - 3/12 = 1/12 1/4 - 1/5 = 5/20 - 4/20 = 1/20 1/10 - 1/11 = 11/110 - 10/110 = 1/110