A bonus number, also called an alternate number or supplementary number, is an extra number drawn in a lotto game in addition to the main set of numbers. There can be a single bonus number or multiple bonus numbers, depending on the game. There are 2 basic types of bonus number games:

• When a bonus number from the same number pool as the rest of the lotto numbers is drawn by a lottery in order to give more prize matching options. Lotto tickets do not have a selection for the bonus number as it is matched within the main set of numbers chosen by a lotto player. This type of game is rare in the USA, but is common in other countries. An example is the United Kingdom National Lottery, which has a 6/49 number field, but the lottery draws 7 numbers from 1-49.
• When a bonus number from a separate number field than the rest of the lotto numbers is drawn by a lottery. This is a powerball type game in which a lotto player does select the bonus number on their tickets. An example is the USA Powerball game, which has a regular number field of 5/55 and a bonus number that comes from a 1/42 number field.