1. First draw a rectangle and divide it into m×n squares (m and n are the digits of two multipliers respectively), and write down two factors on the upper and right sides of the squares respectively.

2. Divide the square into two diagonal lines and record the ten digits and the single digits of the product corresponding to the above numbers respectively.

3. Then, from the bottom right to the top left, add these products diagonally, and when the sum is full, move forward by one.

4. Finally get the result (the numbers on the left and bottom of the square are arranged in turn).

Introduction to grid multiplication:

Square multiplication, 1494 Italian mathematician Bacceli (1445- 15 14) introduced eight kinds of multiplication. The first multiplication is exactly the same as the commonly used pen multiplication, and the sixth multiplication is grid multiplication, also called carpet multiplication.

According to legend, this method was first recorded in the book Lilovati written by Indian mathematician Bashgaro in 1 150. /kloc-was widely spread in Arabia after the 0/2nd century, 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 "patchwork" in his book Arithmetic Unity. There are similarities between the two methods. The line drawing algorithm is more intuitive and simple, and the lattice algorithm is between line drawing and formula.

Extended data:

Similar to dot matrix multiplication, there is also a famous column-longitudinal method, which refers to the column-a longitudinal formula in the calculation process, making the calculation more convenient.