How many unique sudoku puzzles are possible?

Is there a secret to solving sudoku puzzles?

Answer: The most basic strategy to solve a Sudoku puzzle is to first write down, in each empty cell, all possible entries that will not contradict the One Rule with respect to the given cells. If a cell ends up having only one possible entry, it is a "forced" entry that you should fill in.

Why are some sudoku puzzles unsolvable?

Answer: A Sudoku is unsolvable if there is no way to fill in all the spaces without violating one of the rules of Sudoku. An Sudoku is invalid if the clues given violate one of the rules of Sudoku. The minimum number of clues needed for a invalid Sudoku is obviously 2.

What is the key to solving sudoku puzzles?

Answer: The most basic strategy to solve a Sudoku puzzle is to first write down, in each empty cell, all possible entries that will not contradict the One Rule with respect to the given cells. If a cell ends up having only one possible entry, it is a "forced" entry that you should fill in.

Are some sudoku puzzles unsolvable without guessing?

Answer: The vast majority of puzzles don't require the trickier techniques, but there are some which just aren't solvable by simple logic alone, and require various forms of guessing to solve. Some argue that guessing is a form of logic, but it does often mean a lot of erasing!

What are the weird rules for sudoku puzzles?

Answer: The puzzle is called the Miracle Sudoku and it's made by fellow puzzle legend Mitchell Lee. And here are the special rules: “Any two cells separated by a knight's move or a king's move (in chess) cannot contain the same digit. Any two orthogonally adjacent cells cannot contain consecutive digits.”