The Sudoku hard level 4 game 28 is solved by identifying and exploiting an enhanced Swordfish pattern of digits formed by four pairs of locked digits.
Level 4 Game 27 Sudoku hard X wing breakthrough achieved after getting other breakthroughs by double digit parallel digit scan and single digit lock.
Sudoku level 4 game 26 solved by Sudoku hard solution techniques of single digit lock and double digit scan among others. Each technique explained.
The Sudoku Hard level 4 Game 25 is solved by identifying first an X Wing digit formation and then discovering a valid digit by X wing digit reduction.
Very hard Sudoku level 4 game 24 solved by test of linked pairs of locked digit chains resulting in conflict of same digit in two cells of same column.
Very hard Sudoku level 4 game 23 solved by test of linked pairs of locked digit chains resulting in conflict of same digit in two cells of same column.
Very hard Sudoku level 4 game 22 solved by analysis of linked pairs of locked digit resulting in conflict of same digit in two cells of same column.
Very hard Sudoku level 4 game 21 is solved step by step using valid diagonal test of an asymmetric X wing digit formation for easy understanding.
Very hard Sudoku level 4 game 20 is solved step by step using advanced Sudoku techniques and strategy so that it is easy to follow how to solve hard Sudoku.
Very hard Sudoku level 4 game 19 is solved step by step using advanced Sudoku techniques and strategy so that it is easy to follow how to solve hard Sudoku.
