The "-"sign was also invented by Weidemann. Removing a vertical line from the+sign means reducing. These two symbols were officially recognized by everyone, beginning with the formal application of this symbol by the Dutch mathematician Braun Ik in 15 14.
"×": It was first used by American mathematician Audrey in18th century. Multiplication is another expression of increase, so the "+"sign is oblique. Xiao: It was created by Swiss Hannah in18th century. It was invented by the British scholar Le Corde in the16th century. He believes that only these two parallel and equal straight line symbols in the world are the most appropriate expressions of equivalence.