Here's how hard it is: even if you had EVERY POSSIBLE BINGO CARD sprawled out in front of you, your chances of getting a 24-spot cover all in 24 calls is still less than 1/232! There are (7524) = 2.577E19 (that's 25.77 quintillion) ways that the house could pull the first 24 balls out of the hopper (in any order.)