to decide if he wants to stop and bank his points (i.e. score them permanently by writing them down on paper) or if he wants to push his luck and re-roll the dice. if he re-rolls and fails to match colors, he loses all points from this current turn. if he matches, he adds the newly scored points to his previous total and then decides again to push his luck or not.
there are a few special rules if you match all the small dice to the large die. if all six dice are grey, you get an extra 10 points. if all six dice are orange, you get an extra 