The winning numbers were 19, 37, 40, 63 and 69, plus Mega Ball 17.
The win is worth $560 million comes with a cash option for $264.4 million. The Illinois Lottery said the ticket was bought online.
Mega Millions tickets are sold in 45 states, Washington, D.C., and the U.S. Virgin Islands. Tickets are $2 each; in most jurisdictions, players can add the Megaplier for an additional $1 to multiply their non-jackpot prizes.
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Drawings take place at 10 p.m. Central Time on Tuesdays and Fridays.
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The overall odds of winning any Mega Millions prize are 1 in 24; the odds of winning the jackpot are 1 in 302,575,350.