A Lucky 31 bet consists of five selections that combine to make 31 different bets. These are: 5 singles, 10 doubles, 10 trebles, 5 four-folds, and 1 five-fold acca. It’s most commonly used in horse racing. You need at least one selection to win in order to claim anything back from a Lucky 31 bet. Use Paddy’s Lucky 31 bet calculator here.