Challenge your mind today with a logic puzzle.

Courtesy of Wikipedia:

Sudoku (数独, sūdoku^?, listen (help·info)) (English pronunciation: /suːˈdoʊkuː/) is a logic-based,^[1][2] combinatorial^[3] number-placement puzzle. The objective is to fill a 9×9 grid so that each column, each row, and each of the nine 3×3 boxes (also called blocks or regions) contains the digits from 1 to 9 only one time each. The puzzle setter provides a partially completed grid.

Completed puzzles are usually a type of Latin square with an additional constraint on the contents of individual regions. Leonhard Euler is sometimes incorrectly cited as the source of the puzzle, based on his related work with Latin squares.^[4]

The modern puzzle was invented by an American architect, Howard Garns, in 1979 and published by Dell Magazines under the name “Numbers in Place.”^[5] It was popularized in 1986 by the Japanese puzzle company Nikoli, under the name Sudoku, meaning single number.^[6] It became an international hit in 2005.^[7]

A lot of local newspapers have started to run these puzzles daily.  Personally I turn to the web to get my fix.  Web Sudoku has a ton if you are interested.