The chances of winning a lottery jackpot are principally determined by several factors: the count of possible numbers, the count of winning numbers drawn, whether or not order is significant and whether drawn numbers are returned for the possibility of further drawing.

In a typical 6 from 49 lotto, 6 numbers are drawn from 49 and if the 6 numbers on a ticket match the numbers drawn, the ticket holder is a jackpot winner - this is true regardless of the order in which the numbers are drawn. The odds of being a jackpot winner are approximately 1 in 14 million (13,983,816 to be exact).

To put these odds in context, suppose one buys one lottery ticket per week. 13,983,816 weeks is roughly 269,000 years; In the quarter-million years of play, one would only expect to win the jackpot once.

The odds of winning any actual lottery can vary widely depending on lottery design. "Powerball" is a very popular multistate lottery in the United States which is known for jackpots that grow very large from time to time. This attractive feature is made possible simply by designing the game to be extremely difficult to win: 1 chance in 146,107,962. That's over ten times smaller than the example above. Powerball players also pick six numbers, but two different "bags" are used. The first five numbers come from one bag that contains numbers from 1 to 55. The sixth number -- the "Powerball number" -- comes from the second bag, which contains numbers from 1 to 42. To win a powerball jackpot, a player's five regular numbers must match the five regular numbers drawn and the Powerball number must match the Powerball number drawn. In other words, it is not good enough to pick 10, 18, 25, 33, 42 / 7 when the drawing is 7, 10, 25, 33, 42 / 18. Even though the player picked all the right numbers, the Powerball number at the end of the ticket doesn't match the one drawn, so the ticket would be credited with matching only four numbers (10, 25, 33, 42).

Most lotteries give lesser prizes for matching just some of the winning numbers. The Powerball game described above is an extreme case, giving a very small payout (US$3) even if a player matches only the Powerball number at the end of your ticket. Matching more numbers, the payout goes up. Although none of these additional prizes affect the chances of winning the jackpot, they do improve the odds of winning something and therefore add a little to the value of the ticket.

The expected value of lottery bets is often notably bad. In the United States, an expected value of -50% is not atypical. This has led some people to deride lotteries as "the math tax" or a "tax on stupidity."

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia.