[BruceZ]

The only thing your answer doesn't account for are the times that you get a number with both digits the same like 33, in which case if you match the forward, you will also match the reverse. Your chance of getting a number like this is 1/10, and assuming you get paid for both forward and reverse, those numbers have an ev twice as high. Here is how you would compute the total ev:

(.9*.01 + .1*.02)(3*250 + 3*500) + .01(300) = $27.75

Now suppose you only got paid for the forward when you match both. In that case, the ev of these 10 numbers will be reduced. In that case the ev is:

(.9*.01)(3*250 + 3*500) + (.1*.01)*500 + .01(300) = $23.75

In both cases I've assumed you get paid double if you have duplicate cards. If this isn't the case, it won't matter much since this is rare.