Draw a rectangle first, divide it into m×n squares (m and n are the digits of two multipliers respectively), and write down two factors on the top and right side of the square respectively. Then divide the square into two parts by diagonal, and record the ten digits and single digits of the product corresponding to the above numbers respectively. Then these products are added diagonally from the bottom right to the top left, and when they reach ten, they move forward by one. Finally, the results are obtained (the numbers on the left side of the box are in order)

Extended data:

Write the first factor 46 on the top of the grid diagram and the second factor 75 on the right side of the grid diagram. Then, write the 42 of 6×7=42 in the box below 6, write the number 4 of 10 on the diagonal, and write the number 2 below the diagonal. Similarly, write 4× 7 = 28. 6×5=30; The grid says 4×5=20.

Then add up all the numbers on the same diagonal from the far right. If there is only one 0 on the rightmost diagonal, write 0 at the end of the diagonal; The second diagonal, 2, 3 and 0 add up to 5, so write 5 at the end; The third diagonal, 4, 8 and 2 add up to 14, so write 4 at the end and carry 10 to the fourth diagonal; The fourth diagonal has 2, 1 equals 3, so write 3 at last. Finally, write down 3450 from left to right and from top to bottom, so 46×75=3450.

References:

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