Adding Doubles Worksheets | K5 Learning Adding doubles practice worksheets. Doubles (2+2, 3+3, and so on) are key math facts to memorize; they can be used to quickly solve other addition math facts in two steps: solving the doubles fact and then adding or subtracting from that sum. Worksheet #1 Worksheet #2 Worksheet #3 Worksheet #4 Worksheet #5 Worksheet #6.