A 'Math Camp' Sudoku
By Don Allen

The Sudoku epidemic that has peaked in North America in recent months provides a superb example of the kind of investigation that shows potential as a collective 'Math Camp' activity.

Sudoku, the 9 x 9 'complete the pattern' array is American and not Japanese in origin, having been featured in a New York -area puzzle magazine 25 years ago, before having taken Japan, and much of the rest of the world, by storm. It has returned to North America, and with a vengeance.

The standard Sudoku requires that you complete a pattern partially given, in a unique manner, each of nine symbols (most commonly the digits 1 through 9) appearing in each row, each column, and each outlined 3 x 3 square, exactly once.

Sudoku is stricktly mathematical, the pattern itself being a Latin Square (with additional constraints). The numerals, however, are mere symbols -- you don't add or otherwise manipulate them. They could as easily be letters, business symbols, or planetary signs.

You readily discover rules and techniques as you solve, and solving together can be good fun. The illustrated Sudoku challenge uses nine letters, and when correctly solved 'spells out' as a row, column, or 3 x 3 square, three words.

Where to begin? Well, the top cell in the 2nd column can have but one value, the eight other symbols already occurring in its row, column, or 3 x 3 square. And W (there are lots of them) has only one place to go in the lower-left 3 x 3 square.

The best article I've read on Sudoku appeared in Focus, the Mathematical Association of America newsletter for January 2006. A college library would be a good place to seek it.

A Literal Sudoku
(three words)

 W D O E T M W O C E y D W y O W M y I O y W T W D T C I M y I D M

Bright Math Camp