odds

Odds provide a measure of the likelihood of a particular outcome. They are calculated as the ratio of the number of events that produce the outcome to the number that don't. Odds are commonly used in gambling and statistics.
Odds can be demonstrated by examining rolling a six-sided die. The odds of rolling a 6 is 1:5. The odds of rolling either a 5 or 6 is 2:4, or simplifying it 1:2. The odds of not rolling a 5 or 6 is the inverse 2:1. The probability of an event is different, but related, and can be calculated from the odds, and vice versa. The probability of rolling a 5 or 6 is the fraction of the number of events over total events or 2/(2+4), which is 1/3, 0.33 or 33%.When gambling, odds are often the ratio of winnings to the stake and you also get your wager returned. So wagering 1 at 1:5 pays out 6 (5+1). If you make 6 wagers of 1, and win once and lose 5 times, you will be paid 6 and finish square. Wagering 1 at 1:1 (Evens) pays out 2 (1+1) and wagering 2 at 1:2 pays out 3 (1+2). These example may be displayed in many different forms:

Fractional odds with a slash: 5 (5/1 against), 1/1 (Evens), 1/2 (on) (short priced horse).
Tote boards use Decimal or Continental odds, the ratio of total paid out to stake: 6.0, 2.0, 1.5
In the US Moneyline. A positive number lists winnings per $100 wager; a negative number the amount to wager to win $100 on a short priced horse: 500, 100/-100, -200.

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