A KAKURO puzzle is constructed on a crossword grid just like a standard crossword, but the digits 1 to 9 are used instead of the letters of the alpahabet. In a
standard KAKURO puzzle, the Across and Down clues are simply the
sums of the digits in the across and down
words. A
variant of this standard is to use the
products of the digits for the clues. Magnum Opus will make both of these variants.