This is a theme of digital graphics. As can be seen from A, the long side * * * has six line segments, and the wide side has one line segment to form six rectangles. As can be seen from B, the long side has six line segments, the wide side has three line segments, and * * * has 18 rectangles. As can be seen from C, the long side has 6 line segments, the wide side has 6 line segments, and * * * has 36 rectangles. It can be seen that the total number of rectangles is obtained by calculating several line segments on the long and wide sides and then multiplying them.