Let the number in the middle of the cross box be X, then the number in front is x-2, the number behind is x+2, the number above is x- 16, and the number below is x+ 16. Add these five numbers to get: (X-2)+X+(X+2)+(X

In other words, the sum of the five numbers in the cross box is always five times the middle number. (This is the most critical)

To meet the conditions, this number must be divisible by 5.

According to the above conclusions, it is obvious that 20 12 does not meet the requirements. 20 15 meets the requirements.

The middle number is: 20 15÷5=403.

The previous number was: 403-2=40 1.

The last number is: 403+2=405.

The last number is: 403- 16=387.

The next number is 403+ 16=4 19.