## Recreational Math## Mathematical Games |

## What are betting odds and how are they determined? |

Betting odds are usually written in the form *r:s,* in which *r* is the “chances for” and *s* is the “chances against.” This can be stated as: *“r* to *s”* or “chances for to chances against”; or “s to r” or “chances against to chances for.” But note that odds of 1:1 are said as “one to one” *not* “one out of one.” Odds are usually calculated as follows:

Using a 52-card deck as an example, the odds of drawing a king from the deck are 1 in 12—or 4:(52 - 4) = 4:48, which equals 1:12.