Expected value

I can't figure out how to set this up. The compilation of data is boggling my mind. Do i use the 0,1,2,3,4,5,6,7,8,9 to figure my probabilities?

a lottery entitled "Big 4". To win, a player must correctly match 4 digits from a daily lottery in which four digits are selected. Digits are the numbers 0-9, so there are 10 digits. If the payoff for a $100 bet is $10000, what is the expected value of winning? Is it worth it?

Thank you,
Here's a start. Think of a raffle with tickets numbered from 0000 to 9999. How much does it cost to buy all the tickets? How much do you win?
Figure out the sample space of all 4-digit tickets. From there, the probability of winning should be straight-forward. Then the expected value is the sum of x*p(x). x is the payout and p(x) is the probability.
Thank you.
Does that mean that each digit could have 10 possible options? Meaning that it could be 0123? so it would be basically 10x10x10x10 or 10,000 possibilities? So my probability would be 1/10,000?

***i just answered my own question. :)
thank you for your help
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