43 Latin squares
For a few years the world has been Sudoku mad. Across the land, pens and pencils are
chewed waiting for the right inspiration for the number to put in that box. Is it 4 or is it
5? Maybe it’s 9. Commuters emerge from their trains in the mornings having expended
more mental effort than they will for the rest of the day. In the evening the dinner
burns in the oven. Is it 5, 4, or maybe 7? All these people are playing with Latin squares
- they are being mathematicians.
Sudoku unlocked
In Sudoku we are given a 9×9 grid with some numbers filled in. The object is
to fill in the rest using the given numbers as clues. Each row and each column
should contain exactly one of the digits 1, 2, 3, ..., 9, as do the small constituent
3×3 squares.
It is believed that Sudoku (meaning ‘single digits’) was invented in the late
1970s. It gained popularity in Japan in the 1980s before sweeping to mass
popularity by 2005. The appeal of the puzzle is that, unlike crosswords, you don’t
have to be widely read to attempt them but, like crosswords, they can be