Sudoku1 - Varient Magic Square

Varient : Magic Square

The area with star marks includes a magic square, i. e., the sums of any row, any column and both main diagonals in this area are always the same.
By pushing button

of the toolbar, possible values are filtered using combinations available, if only one possible solution. In the resolution methode, select the method "Variant" to take into account these combinations.

Here is an example of grid:

In a 3x3 magic square, sum of all lines is equal to (1+2+3+…+9)=45. So sum of each line, colomn or diagonal is 15. The only possible value in center of the magic square is 5, other being the 4 couples with sum 10 (1+9; 2+8;3+7; 6+4).

Value 9 can not be in an edge, as they should be 2 ways to make 15 excluding 5. We have only combination 9+4+2, so 9 is in center of external line or column. By extension other possible value in center of external line or column can be 1, 3 and 7.

In our grid, 9 can not be in center vertical line. So 3 and 7 should be in center vertical line. So 3 is found.