The first contact with the complete square formula was learned in the sixth grade of primary school mathematics, when mathematics was wide-angle, number and shape. With the help of the square figure, this big square is divided into two small squares and two identical rectangles.
That is to say, a square with a side length of 6 cm is divided into a square with a side length of 2 cm and a square with a side length of 4 cm and a width of 2 cm. In the formula, 6×6=2×2+2×4+2×4+4×4.