2d 20D20s 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.With 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.