[AaronBrown]

Sheetwise gave you an excellent answer, but there are two important caveats. First, this assumes that the individual drawings are independent. Second, it is the chance that you win one or more times out of ten. The expected number of wins out of ten draws is 0.5 (this is true whether the draws are independent or not). The difference between this and 0.40126 is due the the possibility of winning two or more times.