He memorized this square:
|
8 |
11 |
14 |
1 |
|
13 |
2 |
7 |
12 |
|
3 |
16 |
9 |
6 |
|
10 |
5 |
4 |
15 |
The columns, rows, and diagonals add to 34.
Then he added enough to each of the bolded numbers to change the total from 34 to 53. Note there is one bold number on each row, column, and diagonal.
EDIT: Note in this square any 2x2 sub-square adds up to 34 as well. But if you add to the bolded numbers, then this breaks.
13 + 2 + 3 + 16 is equal to 34 in this square
but
32 + 2 + 3 + 35 is not equal to 53.