The Mega Million jackpot is now $640 million dollars. Friday morning the jackpot was $540 million. The lottery said an 'unprecedented sales nationwide' caused $100 million jump.

Virginia Lottery Executive Director Paula Otto said most people wait until the day of the drawing to buy tickets, so it has been a challenge to predict just how much the jackpot will increase.

'We expect to sell somewhere between 12 and 14 million tickets [in Virginia] for the drawing,' Otto said. 'We'll sell close to nine million of those on Friday.'

Otto said during the busiest part of the day, she expected the lottery to sell 17,000 tickets per minute. She expected at least half of all adults in Virginia to buy a Mega Million ticket for this drawing.

'We're pretty sure we'll have a winner, probably more than one, just based on the number of tickets being sold,' Otto said. 'If by some chance we did not have a winner, I think we'd probably be, potentially be, in the billion-dollar category.'

Otto said it only takes one ticket to win but lottery pools have better odds. Get your lottery pool agreement here:

http://www.contractcentral.com/lottery/

Mega Million jackpot is now $640 million dollars.