Lets assume that Jim is playing a 6/49 lottery and that he purchases 91 ticket with 8 encore plays.
The 6/49 works that you choose 6 numbers 1-49 and 7 numbers are drawn. A 3 number match is considered a win.
With encore (keeping it simple) a player has 2, 1 in 10 chances of winning something per play.
What are the odds that nothing will be won from this lot of tickets?