Sudoku tips

Pick one digit and scan the board for where it can still fit. Work across related rows, columns, and boxes instead of staring at one empty square for too long.

A row or box with many givens is a good place to begin because fewer candidates remain.

A naked single is a square with only one possible digit. Once every other digit is blocked by its row, column, or box, place the remaining digit.

A hidden single is a digit that has only one possible position inside a row, column, or box, even if that square has other notes.

If two squares in the same row, column, or box can only be the same two digits, those digits are reserved for those squares.

That pair can remove the same two candidates from the rest of the row, column, or box.

Notes should reduce work, not create clutter. Add notes when a square has a small set of realistic candidates.

After placing a digit, clear that digit from notes in the same row, column, and box. Then look for singles created by the change.

When every square looks equally possible, stop entering numbers. Re-scan the most constrained boxes and compare them with nearby rows or columns.

A short pause often reveals a missed single faster than adding more notes.