A Sudoku a day keeps insanity at bay. That, as my old grandmother used to put it, was derived from an ancient Confucian proverb about the importance of keeping an active mind. For, like the best well-oiled machine, one's grey matter needs regular exercise and plenty of maintenance to keep it tikkety-boo.

Now the simply fiendish arithmetical challenge that has so enthralled the world can be yours every day of the year, without so much as having to buy a newspaper. Simply rip off the top of the block and lo, another challenge lies beneath. Magic.

Sudoku, for those of you who don't give a jot about these trifling matters, is a number placement puzzle that means 'single number' in Japanese. Played on a part-populated 9x9 grid made up of 3x3 sub-grids called 'regions', the goal is to fill in the empty cells, one number in each, so that each column, row, and region contains the numbers 1 to 9 once and once only. There. That wasn't so awful now, was it?

This notelet-style block is designed to sit atop one's desk, enabling one to take a vigorous mental workout over a nice cup of tea first thing in the morning, or subject one's brain to a pounding when laboriously copying files into a spreadsheet, or somesuch office chore.

With a full 365 Sudoku puzzles to last the whole year covering beginners, medium and expert levels, there's no aptitude that won't be satisfied, and no Sudoku addict that won't be sated.

Consider yourselves Sudokud-out.