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On the calculator,+-.X. What is the key?
Do the "add, subtract, multiply and divide" keys.

1, addition symbol "+":1489 German mathematician Weidemann first used it in his mathematical works. However, it was not until the 6th century A.D./KLOC-0 that the plus sign became popular under the advocacy and propaganda of the German mathematician Veda.

2. Subtraction symbol "-":It was first used by German mathematician Weidemann in his book 1489, but it was not until 1630 that the "-"symbol was recognized by everyone.

3. Multiplication symbol "×":1631year. The British mathematician Oughtred proposed to use "×" to represent multiplication. But Leibniz is in favor of multiplying by "". "X" and "X" are at loggerheads, and these two operation symbols are still used today.

4. Division symbol: The British mathematician Orkut used ":"in 163 1 year to indicate "division" or "ratio", and Leibniz also proposed ":"in 1684. At that time, it was also advocated to use the dividing line "-"to represent the division (such as the current score). 1659, Switzerland's Rahn combined two division symbols into one and got the familiar division symbol \ \.

Extended data

Additive commutative law: A+B = B+A.

Additive associative law: (a+b)+c=a+(b+c)

Addition has several important properties. It is interchangeable, which means that the order is not important, it is interrelated, which means that when more than two numbers are added, the order in which the addition is performed is not important. Repeatedly adding 1 is the same as counting; Adding 0 will not change the result. Addition also follows related operations such as subtraction and multiplication.

Addition is one of the simplest digital tasks. The most basic addition: 1+ 1 five-month-old babies and even other animal species can be counted. In primary education, students are taught to calculate the superposition of decimal numbers, starting with one digit, and gradually solving the more difficult number calculation.