I figured something out too (which is very surprising considering I don't know anything about scripting) but it's not what you wanted, just something slightly different:
1. Make two variables, VARIABLE and COOL.
2. Make new link on page you want.
2. Go to the link you want to change the variables and press the := button. Put in %VARIABLE := %COOL + 1D2 (or whatever you want to put for the random number like, 3D2, 1D4, etc.)
3. Make sure it works.
This way makes it so whatever %COOL is, it would add in with %VARIABLE. Do you guys get where I'm coming from?