The key is the selection of diagonal number, which was used three times.

For odd cells, the key is which number you put in the middle cell, because it is used four times (the diagonal number is used three times) and the other numbers are used only twice.

In addition, the rule is: for n squares, the number 1 ~ n is required, so each row (column, diagonal) satisfies that its sum is equal to (1+2+3+...+N).

√~ n = n *(n+ 1)

(2√~ n)。

：

This is the construction method of any odd-numbered Rubik's cube, which China discovered as early as Dayu's flood control. Yang Hui, a mathematician in the Song Dynasty, concluded: "The arrangement of nine sons is easy to go up and down, more harmonious to the left and right, and four dimensions are prominent."

Jiugongge, a digital game, originated from Hutuluo, which are two mysterious patterns handed down from ancient China. It has always been regarded as the birthplace of Heluo culture and the source of Chinese civilization, and is known as the "Rubik's Cube".

According to legend, in ancient Fuxi, the dragon horse appeared from the Yellow River in Mengjin County, northeast of Luoyang, bringing a "river map" to Fuxi. Based on this, Fuxi became a gossip and later became the source of Zhouyi.

Another legend is that when Yu was in Dayu, a turtle emerged from Luohe in Silonen County, Luoyang, carrying a "Luoshu" on his back and gave it to Yu. Dayu succeeded in harnessing water on this basis, so he decided that the world was Kyushu.

Based on this, nine chapters of Dafa were established to govern society, which was circulated in history books and named Hong Fan. The Book of Changes says, "Rivers paint, Luo writes and sages write", which refers to these two things.