...consider what split jackpots do to the expected value. Writing for Business Insider, Walter Hickey does the math on playing Powerball.
Hickey plots lottery participation as a function of Jackpot value, runs linear and polynomial regressions on this data, throws in a chart showing how the probabilities of different numbers of winners change with number of tickets sold, compares the cash up-front and 30-payment annuity options for payout, and concludes...
Taxes will probably mean that it is never profitable or sensible to play the lottery.
Read the analysis.