The principle of "dot matrix multiplication" is to draw a rectangle first and divide it into small cells with corresponding digits according to the digits of two multipliers. Write down the digits of the multiplier and the multiplicand in turn at the edge of the cell, divide the cell into two parts with diagonal lines, and record the 10 and 1 bit of the product corresponding to the above digits respectively. Add these products diagonally from right to left, add up to ten, and you will advance by one.

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Lattice multiplication is two calculation methods of number multiplication first proposed by Indian mathematician Blache Garrow in 1 150 in his book Lirowati. /kloc-After the 0/2nd century, it was widely spread to Arabia, and then spread to Europe through Arabs, and soon became popular in Europe. This method was later introduced to China, and Cheng Dawei, a mathematician in China in the Ming Dynasty, called it foreshadowing in his book Arithmetic Unity, but there are also similarities.