Lottery officials say the prize is growing quickly Friday because so many people have been purchasing the $2 tickets. The jackpot has grown by an estimated $236 million since the last drawing on Wednesday.
The last jackpot was won on March 30, so it's been growing for about six weeks. The next drawing is Saturday night.
The largest jackpot ever was a $656 million Mega Millions prize won in March 2012. The prize was split three ways with winners in Illinois, Kansas and Maryland.
Odds of winning the Powerball jackpot are about 1 in 175 million.