The Kakuro Challenge: Easy, Standard, Hard, Extreme Kakuro Puzzles

Kakuro is one of the most popular Japanese number logic puzzles. A sort of hybrid of Sudoku and Crossword, it is one of the most fun yet challenging puzzles to solve. The principle is simple. Insert numbers in each cell in an entry so that when they are added together they equal the numbered clue for that entry. So, sharpen your brains and have fun!