Here's some groundwork laid out on EX 2 and EX 3. On EX2 we have to use list.str to separate the digits, then find a way to sum every other number. Not that hard.

As for as EX3 goes, I found that rps_winner should subtract the value (0,1,2) of P2 from P1 and modulo 3 (because there are three possible options. Please feel free to correct my code.

Here's another version (changes to EX3 in particular).