The "+"sign begins with the prefix p of the English plus sign. In order to speed up, write two letters side by side, so et slowly becomes "+".
Similarly, for the convenience of drawing, the number "-"uses the prefix m of English monus (minus sign) and gradually becomes "-".
The symbol "X" means multiplication, which was put forward by British mathematician Oughtred in 16 18. "X" is another way to indicate increase, so the "+"sign of "X" is oblique. Leibniz, a German mathematician, thinks that "×" and the letter "ⅹ" are easily confused, and advocates using "?" Stands for multiplication. Later, "X" and "?" It all means multiplication.
The symbol \ stands for division, which was also put forward by British mathematician Oughtred. He used ":"to represent division or ratio, and some people used "horizontal line" to represent division, for example, a/b stands for B divided by A. Later, some people combined these two symbols and got "". The symbol of division is Swiss mathematician Rahn, and a horizontal line separates two points, indicating the meaning of demarcation.