Fallout: The Roleplaying Game - 2d20 Rules Booklet

2d 20With Roll A Dice & Dice Roller, you can roll 4, 6, 10, or 20 dice. Have a specific number of dice to roll? A user-friendly interface will allow you to change the total number of rolls with just one click.D20s are used for resolving skill tests, and for rolling on certain large tables. Often, two or more d20s will be required. This is noted as Xd20, where X is the number of dice to be rolled.