1, nine consecutive numbers, respectively recorded as 1-9 in ascending order, this title is:1-21; 2-22; ……

9-29;

2. Fill in the following: four corners, from left to right and from top to bottom, fill in even numbers in turn: 2, 4, 6 and 8; The rest are filled with odd numbers from bottom to top and from right to left: 1, 3, 5, 7, 9.

3. Replace the corresponding number in the 1 rule.

Attached:

One of the most primitive filling methods of nine squares;

2 9 4 corresponds to: 22 29 24

7 5 3 27 25 23

6 1 8 26 2 1 28