Part 1: Add the Doubles. Some of these facts will reappear in Part 3. Part 2: Solve the problems that add 1, 2, or 3. Work quickly and carefully. Part 3: Add (do not count one by one). First, cross off the two addends that make a Double, then quickly add the third number (1, 2, or 3). The first one has been done for you. Try to finish this section in less than three minutes.