First of all, expand knowledge.

1, multiplication

Multiplication is a shortcut to add up the same numbers. The result of its operation is called product, and "X" is the symbol of multiplication. From the philosophical point of view, multiplication is the result of qualitative change caused by additive quantity.

The multiplication of integers (including negative numbers), rational numbers (fractions) and real numbers is a systematic summary of this basic definition.

Multiplication can also be seen as calculating the reputation of objects arranged in a rectangle (integer) or finding a rectangular area with a given side length to celebrate this letter. The area of the rectangle does not depend on which side is measured first, which shows the exchange property.

The product of two measured values is a new type of measurement, for example, multiplying the length of two sides of a rectangle to get its area, which is the theme of size analysis.

2. The development of multiplication

In the process of arithmetic development of various civilizations, the generation of multiplication operation is a very important step. A civilization can successfully develop counting methods and addition and subtraction operations, but it is not so easy to create simple and feasible multiplication methods.

The vertical calculation of multiplication seems simple, but it is necessary to master the formula table of 99 multiplication in advance; Considering this, this vertical calculation is not perfect. It will soon be seen that in the development of mathematics, different civilizations have created different multiplication methods, and some can even abandon the multiplication table completely.

Ancient Babylonian mathematics used hexadecimal, which was confirmed by a piece of ancient Babylonian clay discovered by archaeology. There is a square on this clay tablet with four numbers 1, 24,51,10 on the diagonal. When this clay tablet was first discovered, people didn't know what it meant.

Later, a cow was surprised to find that if these figures were taken as three decimal places in hexadecimal, they would be exactly approximate to the diagonal length of the unit square:1+24/60+51/602+1603 =1.465438+.

The use of hexadecimal has brought great obstacles to the development of multiplication in ancient Babylonian mathematics, because to memorize the multiplication table of 59-59, at least 1000 items must be memorized. By the time you recite it, it is estimated that the final paper has been written.