Module to teach me Symbolic Dice

What are some modules I can look at on how to do simple Symbolic Dice?

I want a d6 and a d8 to roll and show their faces side by side in a separate window or on the board. Is “on the board” possible?

Also, are there any modules that can show me how to perform math with dice roll results?

I want to get the reverse side of a die roll. So if it is a d6 with a roll of 4, I know the reverse side would be ‘=7-4’ as all opposite sides sum to ‘number of sides’ + 1.