In politics, stock markets, space, and the battlefield, tiny software calculation mistakes have had enormous consequences.

Sometimes those fractional cents aren’t stolen—they simply vanish. In the early 1980s, a new stock index at the Vancouver Stock Exchange tracked a steady and mysterious loss in value. An investigation revealed that floor() was being used instead of round(), with the lost fractions of cents accumulating to almost a 50 percent loss of value in 22 months. The programming mistake was finally fixed; the index closed around 500 on a Friday and reopened the following Monday at over 1,000, the lost value restored.

source: ML