Forecasts, tricasts, exactas
These are finishing-order bets. The UK tote names and the North American names are the same arithmetic under different labels. Most pay a pool dividend to a £1 or $1 unit, not a starting-price multiple.
Every order of your runners in the first three. Three horses = six combinations.
Combinations24
Total stake£24.00
Return if that dividend hits£24.50
Profit£0.50
Work it by hand
Straight bets are one combination. Boxed bets are permutations: n × (n − 1) for an exacta or forecast box, n × (n − 1) × (n − 2) for a trifecta or tricast box. Four named in a box trifecta is 4 × 3 × 2 = 24 combinations. A £1 unit costs £24. A quinella on four names is combinations, not permutations: 4 × 3 ÷ 2 = 6.
A key trifecta (one must win, the others fill second and third) is 1 × (n − 1) × (n − 2). A wheel is the same idea with the banked runner locked in one position. Count the holes you have left, then multiply.