1. Looking at the arrangement rules horizontally: each line goes from left to right, which line is it currently in? It starts from the number 1 to the current line number, multiplied by the current line number respectively, and increases from left to right.
2. Looking at the arrangement law vertically: from top to bottom of each column, in which row is it currently, the current column number is multiplied by the current column number respectively, and the numbers increase from top to bottom in turn.
3. Look sideways at the arrangement rules: the outermost hypotenuse is the current number of rows multiplied by the current number of columns, and the two numbers are the same, increasing from top to bottom.
The formula of multiplication is the basic calculation rule of multiplication, division and square root in ancient China, which has been used for more than two thousand years.
Extended data:
In ancient times, the multiplication formula was from top to bottom, starting with "998 1" and ending with "one to one", contrary to the order used now. Therefore, the ancients used the word "99" at the beginning of the multiplication formula as the name of this formula, also known as "99 table", "99 song" and "99 multiplication table". 2065438+In March 2005, the multiplication table of 99 was introduced to Britain.
General 1 and 99 tables only use 9 numbers from 1 to 9.
2. Jiujiu table contains the commutativity of multiplication, so only 8972 is needed, and "9872" is not needed. 9 times 9 has 8 1 product, and the 99 table only needs 1+2+3+4+5+6+7+8+9 =45 product. In the Ming Dynasty, abacus also had 99 tables with 8 1 product. The 99 table of 45 items is called small 99, and the 99 table of 8 1 item is called big 99.
3. Jiujiu watches have existed for at least 3000 years. It was used for calculation from the Spring and Autumn Period and the Warring States Period, and was improved and used for abacus in the Ming Dynasty. The 99 standard is also the basic skill of elementary school arithmetic.
References:
Baidu encyclopedia-multiplication formula table