Roll any combination of dice - 3d6, 2d20, a single d100 - and see each individual die alongside the total. Modifiers are supported, as is rolling a d20 with advantage or disadvantage, so it works for tabletop games as well as for probability demonstrations.
Roll three six-sided dice, add them together, then add 2 to the total. The notation is NdS+M: N dice with S sides each, plus a modifier M.
You roll two d20s and keep the higher one. Disadvantage keeps the lower. Advantage lifts the average result from 10.5 to about 13.8, and is worth roughly a +5 bonus in the middle of the range.