Across the country Friday, Americans plunked down an estimated $1.5 billion on the longest of long shots: an infinitesimally small chance to win what could end up being the single biggest lottery payout the world has ever seen.

The $640 million jackpot has been building up since Jan. 28. The estimated prize dwarfs the previous $390 million record in 2007.

The winning numbers were 2, 4, 23, 38, 46, and the Mega ball was 23.

The rarity of Friday’s jackpot was fueling the fervor. Lines formed at grocery stores, gas stations, liquor stops and other venues across the country.

Hundreds from Utah and Las Vegas streamed in to neighboring California or Arizona to buy tickets because their states don’t participate.

You’re about 20,000 times more likely to die in a car crash than win the lottery, but that doesn’t matter to most people.

“Part of it is hope. … The average person basically has no chance of making it really big, and buying a lottery ticket is a way of raising the ceiling on what could possibly happen to you, however unlikely it may be,” said George Loewenstein, a professor of economics and psychology at Carnegie Mellon University who has studied how rich and poor consumers make a choice to buy lottery tickets.