In order to win the jackpot in Mega Millions, you must match all 5 of the main numbers, plus the Mega Ball. The odds of doing this are 1 in 258,890,850. However, there are other prizes that can be won by matching fewer numbers. For example, if you match just the 5 main numbers (without the Mega Ball), you will win $1 million. The odds of doing this are 1 in 18,492,204. So as you can see, even though the jackpot is very difficult to win, there are still plenty of opportunities to take home a smaller prize.