Don Colton's Risk Dice Roller

(Risk is a trademark of Parker Bros / Hasbro for their board game.)
Wikipedia Article, Attacking

How many attacking armies
How many defending armies
How many skirmishes (max)

Skirmish 1   2 2 4   3 3 attacker loses X, defender loses X
Skirmish 2   3 1 4   5 3 attacker loses X, defender loses X
Skirmish 3   4 1 1   4 6 attacker loses X, defender loses X
Skirmish 4   2 3 4   4 2 attacker loses X, defender loses X