Bingo cards

Canadian and American bingo cards are flat pieces of cardboard or non-reusable paper which contain 25 squares arranged in five vertical and five horizontal rows; Dual dab, or "double-action" cards have two numbers in each square. Each space in the grid contains a number, except for the centre square, which is considered filled. The highest number used is 75. The letters B, I, N, G, O are pre-printed above the five vertical columns, with one letter appearing above each column. The center space is marked "free." The printed numbers on the card correspond to the following arrangement: 1 to 15 in the B column; 16 to 30 in the I column; 31 to 45 in the N column; 46 to 60 in the G column and 61 to 75 in the O column.

There are 552,446,474,061,128,648,601,600,000 (five hundred fifty-two septillion, four hundred forty-six sextillion, four hundred seventy-four quintillion, sixty-one quadrillion, one hundred twenty-eight trillion, six hundred forty-eight billion, six hundred one million, six hundred thousand) possible arrangements of the numbers on a bingo card.

Each card has a unique serial number to permit quick verification by computer.