Numbo is played on a 6x6 grid. Players take turns entering numbers from 1 to 36 in empty spaces of the grid. Each number must be in the same row or column as the previous number, with no intervening numbers. Whoever enters the last number scores it. A player may resign rather than playing in order to deny their opponent points. A number of rounds should be played. Each round is started at the number after the last used in the previous round, cycling back to 1 after 36. The first edition of the game (Numerate) used a 5x5 grid and had the cyclic number usage as a variant.