David refuels his car afier every two days, Mary refuels hers after every four days while Ken refuels his after every eight days. If they all refuel their cars on 3rd March 2013, on which date did they refuel their cars together again?

David == March 3, 5, 7, 9, 11, 13, 15, 17

Mary -- March 3, 7, 11, 15, 19

Ken -- March 3, 11, 19