Addition Level 4: Mixed 1d/2d + 1d. answer-window addition. 1. Fill tens36 + 9Step 1: Fill tens36plus93raw windows3 + 0 = 3 then release 3running strip3Tens window: 3 + 0 = 3. Hold 3; wait for carry from the next window.2. Fill onesStep 2: Fill ones36plus9315raw windows6 + 9 = 15 then keep 5; carry waitsrunning strip35Ones window: 6 + 9 = 15. Hold raw 15; settle carry later.3. Settle carryStep 3: Settle carryKeep ones; carry moves left.raw windows3 | 15settled digits4 | 5answer 45Settle raw 3 | 15 into 45; keep ones and move carry left.
