Look sharp and get your brain in gear. The plain scientific fact is that your brain is a well-oiled calculating machine, performing truly unimaginable number-crunching to simply keep you upright. It's only when it comes to doing a crossword or reading a map that beffudlement sets in.

So don't give yourself over to discombobulation. Keep your own organic supercomputer in fine fettle and it will jolly well look after you into your old age, not to mention enabling you to partake in dazzling conversation, complete sudoku puzzles in record time and generally be an all-round clever-clogs.

This compendium of some of the world's finest brain-teasers is chock-full of mind-bending challenges to enable you to flex your intellectual muscles when you're on your own, or with chums round the kitchen table. Far from being open-ended in nature, these challenges are set against the clock, so there's much pitting of wits all round.

Comprising a whole stack of varied puzzle cards, the competitor is required to shift his modus operandi from lateral and logical thought; causing severe mental contortion in the so-doing. There are no tricks and no tomfoolery - just a set of questions designed to elicit a logical answer based on swift calculation, sheer mental agility and all-round intellectual stamina.

Good luck, men.