Once Considered Absurd

Negative numbers were resisted for centuries. The ancient Greeks rejected them outright — how can a length be less than nothing?

Yet the Chinese were already using red and black counting rods for positive and negative amounts by 200 BC. In India, Brahmagupta wrote the first clear rules for negative arithmetic in 628 AD, including the line "a debt subtracted from zero is a fortune."

Europe held out far longer. As late as 1758, mathematician Francis Maseres complained that negatives "darken the very whole doctrines of the equations."