I have created a free app for Android which will tell you the odds involved in an attack in the game of RISK.
Either search for "Risk Attack Odds Calculator" in the google play store or go to this link: https://play.google.com/store/apps/details?id=com.JakeKranz....
You enter how many dice the attacker will roll, attacker high and low die modifiers, how many dice the defender will roll, and defender high and low die modifiers.
You then choose if you just want to do a straight number of rolls or if you want to enter the amount of armies involved in the attack.
If you choose number of rolls, the app will tell you the odds of the attacker losing two armies, the defender losing two, or each losing one. It will also tell you about how many armies the attacker can expect to defeat and how many you can expect to lose over the number of rolls.
If you choose number of armies, the app will tell you the odds that the attack succeeds and break that down by how many armies the attacker will lose. It will also tell you the odds the attack fails and break that down by how many armies the defender will lose.
Like I said, the app is free. Please give it a try.
I am interested in hearing suggestions for improvements and reports of any bugs. I am also considering making a paid version, if anyone thinks that would be useful.
Thanks! And don't be afraid to click on those ads!