One of the little pleasures of our annual winter vacation is an evening Bingo party. After a day of sledding and cross-country skiing, it's relaxing to indulge in a social game that requires minimal thought, affords young and old the same chance of winning, and has a strong element of suspense.
To play Bingo, each player has one or more cards divided into squares. Each card has five rows and five columns. The columns are labeled from left to right with the letters "B," "I," "N," "G," and "O." The center square is designated "free." The five squares in column B contain different numbers selected from the interval 1 to 15. Column I contains five numbers from the interval 16 to 30. Column N contains four numbers from the interval 31 to 45. Column G contains five numbers from the interval 46 to 60, and column O contains five numbers from the interval 61 to 75.
An announcer randomly sele