1. The grids are always nine cells wide by nine cells long.
   The clues given are sums.
2. You can’t repeat a digit within a designated group of cells.

Similar to sudoku, kakuro has a rule that you cannot repeat a digit within a designated vertical or horizontal group of cells. Only do sudoku grids have to be nine cells by nine cells large, and only in kakuro are the clues sums.

1. top row and middle column
   bottom row and leftmost column
2. top row and leftmost column

The top row and leftmost column are usually shaded and contain many of the “clues.”

1. two
   three
2. four

Three solution sets are possible: 2, 3, 4; 1, 3, 5; 1, 2, 6. Note that 3, 3, 3 can’t work due the no repeat rule.

1. All kakuro puzzles have one unique solution.
   It is possible for some kakuro puzzles to have more than one solution.
2. All kakuro puzzles have more than one solution

Strictly speaking, it is possible to design a kakuro puzzle with more than one solution. However, these are generally considered to be poorly designed.

1. groups of fewer boxes
   groups on the left side of the board
2. groups on the top half of the board

Groups made up of fewer boxes tend to be easier to solve because they tend to have have fewer solution sets.

1. bachelor numbers
   cross numbers
2. cross addition

Kakuro is an abbreviated version of two words: Kasan Kurosu, the Japanese word for “addition” and the Japanese pronunciation of the English word “cross.”

1. None; It’s impossible.
   one
2. two

No solution is possible.

1. an American magazine in 1950
   a Japenese newspaper in 1980
2. a British journal in 1990

The American Dell Magazines first published kakuro in 1950. Decades later, it grew in popularity in Japan and eventually the United States.

1. None; it’s impossible.
   one
2. two

One solution set is possible: 1, 2, 3, 4, 5, 6, 7, 8

1. Nikoli
   Maki Kajii
2. Konami

Nikoli, the same company that popularized sudoku, also was responsible for lifting kakuro out of obscurity.