DES MOINES, Iowa (AP) — Now that the Mega Millions lottery jackpot has topped $1 billion — only the fourth time a lottery game has reached such heights — plenty of people who rarely play the game are considering risking $2 or joining an office pool in hopes of an immense payoff. Buying a ticket is easy, but it’s also easy to be confused about the odds, how the prizes are set and how the winnings will eventually be paid out. DO YOUR CHANCES OF WINNING RISE OR FALL AS THE JACKPOT GROWS?