The number with a minus sign (less than zero) are called negative. These numbers were used by Indian mathematicians already in the seventh century of our era, and the Chinese - even earlier. Indian scientists have tried in life to find examples of the existence of negative numbers, but to no avail. This is a purely abstract concept, is only required to solve complex algebraic equations.
In Europe, negative numbers for a long time did not find recognition. The ancient Greek mathematician Diophantus was called equations that require negative numbers, irrelevant. In the XIII-XVI centuries negative numbers considered by Europeans only in exceptional cases. Another French philosopher, physicist and mathematician rené Descartes in the seventeenth century called them "false number". Only in the second half of the seventeenth century the development of algebra forced the Europeans to "legitimize" a negative number.
