Basic Roleplaying uses a variety of polyhedral dice to obtain random results. These are available in a wide range of sizes, colors, and qualities from games and hobby stores, or other sources. To play, a group needs at least one set of these dice, though it is easier and more convenient if each player has a set. A set of gaming dice includes the following dice: four-sided (D4), six-sided (D6), eight-sided (D8), ten-sided (D10), twelve-sided (D12), and twenty-sided (D20). A percentile die (marked in increments of 10) is also useful.
The most important dice roll in Basic Roleplaying is the percentile dice roll, which is a roll of two ten-sided dice (or one ten-sided die rolled twice). In a percentile dice roll, the first value is the “tens” while the second is the “ones.” If rolling two D10, read the first result as the “tens die”—thus, a roll of 3 and 7 on percentile dice means a result of 37. Generally, with percentile dice, the lower you roll, the better.
Other dice rolls involve multiples, combinations, or dice results that are modified. For example, 3D6 means roll three sixsided dice, 1D10+1D4 means roll one D10 and one D4 and add the results together, D8+1 means roll a D8 and add 1 to the result, and D6−2 means roll a D6 and subtract 2 from the result. Die rolls are never modified to below 0, however. In the example of D6−2, a roll of 1 or 2 still equals 0.