Bingo card cards to overcome the difficulty with randomization. There are two types of Bingo cards. One is a 5x5 grid meant for 75-ball Bingo, which is largely played in the U.S. The other uses a 9x3 grid for U.K. style "Housie" or 90-ball Bingo. Players use cards that feature five columns of five squares each, with every square containing a number (except the middle square, which is designated a "FREE" space). The columns are labeled "B" (numbers 1–15), "I" (numbers 16–30), "N" (numbers 31–45), "G" (numbers 46–60), and "O" (numbers 61–75). A popular Bingo myth claims that U.S. Bingo innovator Edwin
Bingo card culture. Larger patterns, e.g. a diamond pattern consisting of cell positions B3, I2 and I4, N1 and N5, G2 and G4, and O3, are often used by online Bingo games to permit large number of players while ensuring only one player can win. (A unique winner is further desirable for online play where network delays and other communication interference can unfairly affect multiple winning cards. The winner would be determined by the first person to click the "Bingo!" button (emulating the shout of "Bingo!" during a live game).) In this case the number of unique winning cards is calculated as