ROUGH CUT (NO REPORTER NARRATION)<br/> <br />A last-minute ticket-buying frenzy a week before Christmas inflated Tuesday's (December 17) Mega Millions jackpot to $636 million.<br/> <br />It's on the way to becoming the biggest U.S. lottery prize in history, a game official said.<br/> <br />The prize swelled after a spike in sales early on Tuesday before the 11:00 p.m. EST (0400 GMT, Dec. 18) draw, said Paula Otto, Virginia's lottery director.<br/> <br />If the winner chooses to take the lump sum cash option, instead of payments over 30 years, the jackpot would be $341 million, Otto said.<br/> <br />As much as 70 percent of tickets are typically bought on the day of the draw, she said.<br/> <br />The surge of spending pushed the prize closer to the record U.S. jackpot of $656 million, won in March 2012 in a Mega Millions draw.<br/> <br />If no one picks the exact combination of numbers that appear on six randomly selected lottery balls, the prize will keep ballooning until the next draw on Friday, when the numbers were p
