Sudoku Facts You Probably Didn't Know Of

What Is Sudoku?

Sudoku is a puzzle game designed for a single player, much like a crossword puzzle. The puzzle itself is nothing more than a grid of little boxes called "cells". There are 81 cells in total. Sudoku is played on a grid of 9 x 9 spaces. Within the rows and columns are 9 “squares” (made up of 3 x 3 spaces). Each row, column and square (9 spaces each) needs to be filled out with the numbers 1-9, without repeating any numbers within the row, column or square.

Origin of the term 'Sudoku'

The name “Sudoku” is abbreviated from the Japanese suuji wa dokushin ni kagiru, which means “the numbers (or digits) must remain single” or as "the digits are limited to one occurrence". Interestingly, Sudoku was not invented in Japan.


Where It All Began?

Magic Squares

Sudoku’s roots date back to over two thousand years BC in China. This is where it is believed ‘magic squares’ originated. A magic square is a 3 x 3 or 4 x 4 grid with numbers in the rows, columns and diagonal that all result in the same sum.


Latin Squares

Almost 4000 years later, in the 18th century arrives the Latin squares. In the 1700s Switzerland’s Leonhard Euler, a mathematician, mused on removing the summation rule in magic squares. The result was ‘Graeco-Roman Squares’ or ‘Latin squares’ which were the next step in the evolution toward the Sudoku puzzle. These squares were on a 4 x 4 grid where each cell had one of four Latin letters and one of four Greek letters. The solution was to arrange the letters so that each row and each column contained all four Latin and all four Greek letters with no duplicates. He did not use numbers.


The 19th Century Puzzle - Number Puzzle

Number puzzles appeared in newspapers in the late 19th century, when French puzzle setters began experimenting with removing numbers from magic squares. Le Siècle, a Paris daily, published a partially completed 9×9 magic square with 3×3 sub squares on November 19, 1892. It was not a Sudoku because it contained double-digit numbers and required arithmetic rather than logic to solve, but it shared key characteristics: each row, column and sub square added up to the same number.

On July 6, 1895, Le Siècle's rival, La France, refined the puzzle so that it was almost a modern Sudoku and named it carré magique diabolique ('evil magic square'). It simplified the 9×9 magic square puzzle so that each row, column, and broken diagonals contained only the numbers 1–9, but did not mark the sub squares.


Number Place - The First Sudoku

In the 1970s American Howard Garnes created the first real Sudoku puzzle in Indiana. A Latin square with an extra rule -- the numbers 1 to 9 must also be unique within the nine regions of 3 x 3 sub-squares called boxes or blocks. Adding the sub-square rule made the puzzles more challenging and more interesting. In 1979 Dell Puzzle Magazines New York published these puzzles with the name ‘Number Place.’


Sudoku Gets Popular in Japan

The Japanese have always liked puzzles, and crosswords just don't work because the Japanese written language uses characters for each word instead of letters. In 1984 the Japanese magazine Monthly Nikolist started publishing the Number Place puzzles. They were later called Sudoku, an abbreviation from the longer name Suji wa dokushin ni kagiru (‘the numbers must occur once only’). This name stuck and Sudoku became very popular in Japan.


Hong Kong

Wayne Gould, a retired judge and puzzle enthusiast from Hong Kong, found a puzzle book in Tokyo in 1997. He fell in love with Sudoku. He wrote a computer program, which took four years to complete, that generates Sudoku puzzles. In November 2004 Wayne convinced the London Times to print them in their newspaper. About the same time the Conway Daily Sun in New Hampshire started printing Sudoku puzzles.

After that Sudoku started appearing in American and British newspapers and rapidly spread.


Variants in Sudoku

Although the 9×9 grid with 3×3 regions is by far the most common, many other variations exist.

- Classic Sudoku
- Mini Sudoku
- Mega Sudoku
- Irregular Sudoku
- Diagonal Sudoku
- Multi Sudoku
- Sum Sudoku
- Odd/Even Sudoku
- Picture Sudoku
- Chain Sudoku

Fun Facts

- Sudoku only went viral in the Western world in 2004.

- The very first Sudoku World Championships were hosted in 2006 in Italy.

- Arto Inkala, a Mathematician from Finland, claims to have come up with the “world’s hardest Sudoku” in 2012.

- One cannot complete all of the possible Sudoku puzzles in an entire lifetime.

- Thomas Snyder, from the USA, set the Guinness World Record on 20 May 2006 for “the fastest time to complete a Sudoku puzzle with an Easy difficulty grading.” His time was 1 minute and 29.93 seconds.

- While the name “Sudoku” comes from Japan, the Japanese actually call it by its original name, which is “Number Place.”

- The real number of valid Sudoku puzzle solutions has been calculated to be 5,472,730,538 or 5.47*109[ignoring symmetries, rotations etc…].


Written by - Abija P.B.

Edited by - Gunika Manchanda