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The digits must be single

Sudoku was introduced in 1979 in an American puzzle magazine as the “Number Place” puzzle.
It became popular in Japan in 1986 under the title of “Suju wa dokushin ni kagiru”. It means that the digits are limited to a single (unmarried) occurrence. The title was abbreviated to Sudoku. “SU” means digit and “DOKU” means single.


  1. Place a digit from 1 to 9 in each empty cell.
  2. Each row, column, and 3×3 grid bounded by bold lines contains all the digits from 1 to 9.

Don’t forget, “the digits must be single” in a row, column or 3×3 grid!
Otherwise you cannot have all the numbers from 1 to 9 in nine places, right?

Sudoku is very simple to learn, requires no calculations, and provides a surprisingly wide variety of logic situations. All that is required to solve Sudoku is logic and concentration. No wonder Sudoku is among the most popular puzzles in Japan!


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