1/9998 is 1/(10000-2) is (1/10000) / (1 - 2/10000) which is an infinite sum of geometric progression with an initial value of 1/10000 and ratio of 2/10000.

1/9998 is 1/(10000-2) is (1/10000) / (1 - 2/10000) which is an infinite sum of geometric progression with an initial value of 1/10000 and ratio of 2/10000. In other words, x1 = 1/10000; // 0.0001 x2 = x1 + x1 * 2/10000; // 0.0001 0002 x3 = x2 + x2 * 2/10000; // 0.0001 0002 0004 0008 ... Magic O_O [0] http://en.wikipedia.org/wiki/Geometric_progression http://en.wikipedia.org/wiki/Geometric_progression