The brain, just like the body, needs exercise. Some scientists say that doing puzzles may help you to think more clearly. Puzzles could also improve your memory, especially as you get older. One puzzle a year may not make much difference but doing one every day might even prevent mental illness. Sudoku number puzzles which are very popular in Japan, the UK and the USA. In this example, each row, column and box should contain each of the numbers 1 to 6.