The bigger the jackpot, the more likely this will happen.
In August, a Powerball jackpot advertised at $320 million wound up landing at $337 million. The cash - which the Michigan winner chose - rose from $213.3 million to $224.6 million.
In February, a Powerball jackpot touted as $310 million wound up paying $336.4 million.
But what happened in March with Mega Millions was far more mind-boggling.
The annuity jackpot rolled over to $500 million for the March 30 drawing - a staggering jump of $144 million from the previous drawing.
But that half-billion completely underestimated the ensuing buying frenzy. Before the drawing, the jackpot was revised three times, eventually to a staggering $640 million.
And when it came time to pay the three winners - in Maryland, Illinois and Kansas - the actual amount was put at $656 million.
That's $156 million more than the original estimate.
In just a few days.
That was the only jackpot bigger than this Powerball prize.
So, stay tuned. It could be a crazy couple of days.