It is an addition puzzle which should also be called number version of crossword puzzle. A single digit goes into white Massu among [ of 9x9 ] hexes, respectively. Let's expect the number which goes into a hint the number currently displayed on black hex at white hex. The hex black number expresses the sum total of a ranking [ with the hex black right ] number, and the sum total of the number located in a line under black hex. A problem is random, and since it is generated automatically, it can be played almost infinitely.
CrossNumber
