Kakuro puzzles resemble crosswords which use numbers instead of words. The aim of the game is to fill all the blank squares in the grid with only the numbers 1-9 so that the numbers you enter add up to the corresponding clues. When the grid is filled, the puzzle is complete.

Kakuro is thought to originate from the 1960s, and appeared in American games magazines during that time. Dell Magazines came up with the original English name Cross Sums and other names such as Cross Addition have also been used, but the Japanese name Kakuro seems to have gained general acceptance and the puzzles appear to be titled this way now in most publications.

The word Kakuro comes from the Japanese Kasan Kuroso, combining the words ‘addition’ and ‘across’, believed to have been created by Japanese businessman McKee Kaji.

Sparked by Sudoku’s sensational worldwide success, the Kakuro boom in the West started in September 2005 when “The Guardian” and “The Daily Mail” introduced daily Kakuro puzzles in the UK.

How kakuro is played
Kakuro puzzle grids can be any size, though usually the squares within them have to be arranged symmetrically.

Each grid has a starting position like that of a crossword, containing blacked out squares and white squares.

The idea is to fill in the grid with a number from 1 to 9, but each run of numbers can only contain each number once.

Each puzzle has horizontal and vertical lines, which contain a certain number of blank squares, depending on the layout and size of the grid you are playing.

The aim is to enter digits in each answer that sum to the total stated for that answer on the grid.

A number in the bottom half of a box gives a downwards total, and in the top half refers to a horizontal total.