The tricky part of that is knowing which rolls you wanted to monitor. Do you want every d20 monitored? Even for crit rolls that don't crit? What if there is a roll where the player has to roll 4d20 (or some other number greater than 1d20)? What if there is a dropped die... like a 2d20kl1, and the result is a 3 and a 20. The 20 would have been dropped... do you want that counted?