The objective of sudoku game is to fill a 9×9 grid with digits so that each column, each row, and each of the nine 3×3 subgrids that compose the grid (also called “boxes”, “blocks”, or “regions”) contain all of the digits from 1 to 9. The puzzle setter provides a partially completed grid, which for a well-posed puzzle has a single solution. Your job is to use logic to fill in the missing digits and complete the grid. Don’t forget, a move is incorrect if:
- Any row contains more than one of the same number from 1 to 9
- Any column contains more than one of the same number from 1 to 9
- Any 3×3 grid contains more than one of the same number from 1 to 9
The modern version of Sudoku game was invented in 1979 by Howard Garns in USA (where it was called `Number Place’). It became really popular in Japan in the 1980s and in the UK since late 2004. It is now quickly spreading worldwide. The word Sudoku is an abbreviation of a phrase which means “the digits must occur only once”.
1. Easy. A 4 by 4 grid to start off, leading to a 6 by 6 grid.
2. Medium. 9 by 9 grids, but with plenty of numbers already in place and some helpful clues.
3. Hard. The hard puzzles have less numbers already in place and require more strategies to be used.
4. Fiendish and Demonly Headteacher. Only for experts. If you can’t do them try asking your Headteacher! (They might become so engrossed they forget about the detention you got!).