Super Bowl Squares - Probability

[Wulfgang]

Basic scenario we all know: Super Bowl grid pool of 10 squares by 10 squares with the numbers 0-9 on each axis randomly selected. For this question, I am talking about before the numbers for the axes are even drawn, so just a 10 x 10 square pool. What is the expected value of your bet net of your initial cash outlay?

For simplicity, assume it is $5 per square for a total pot for $500.

My contention is that, regardless of how many squares you buy, the net expected value is zero; an example of buying one ticket:

-5 + 500*(1/100) = 0

One of my coworkers vehemently disagrees saying it is:

-5*(99/100) + 500*(1/100) = 0.05

I think he is wrong, please halp!

[Zosi]

He's wrong because his "winning" scenario doesn't take into account that you still spend the $5 to buy in. If you spend $5 on a square and win $500, your net profit is only $495, not $500, which makes it work back out to 0.

-5*(99/100) + 495*(1/100) = 0

[aurik]

Your coworker should be shot for being so stupid.

[Mizango]

Your coworker should be shot for being so stupid.

Summed up nicely. lolcoworker.

[Bkbahamut]

Whats so funny about this... and ironic.. is we did one of these at the superbowl party i went to tonight. Except it was $1 a square, i would have won if the score would have stayed 20-14 lol. So the pool was $100.