As requested by a particular person, I thought I might as well post this so that everyone can see it if they had ever wondered.
In the Mega Millions Lottery, you must choose 5 numbers out of 56 numbers. And then as a special twist you must choose a Mega Ball Number out of 46 possible numbers. The Mega Ball is a separate drawing, but you can still use combinations to solve this problem.
56 nCr 5 = 3,819,816
46 nCr 1 = 46
Now you must multiply the two numbers together to get the exact odds.
3,819,816 * 46 = 175,711,536
You have exactly a 1 in 175,711,536 chance of hitting the jackpot.
Now you may notice that the News says the odds are a nice round number, like around 175 million or 176 million. The truth is that they are totally wrong, but expect that a vast majority of the people won't notice, or even care about them rounding the number for the total number of possibilities.