Rules of XV Sudoku
Classic Sudoku Rules apply. Additionally, if an X is given between two adjacent cells, the digits in those cells sum to 10. If a V is given between two adjacent cells, the digits in those cells sum to 5. If an X or V is not given, the two digits cannot sum to 5 or 10.
A Sudoku XV puzzle consists of a standard Sudoku grid with the addition of X and V markers between neighbouring pairs of squares. X markers show all adjacent pairs of squares where the two values in those squares add up to 10, while V markers show all pairs where the two values sum to 5.