Addition Level 10: 2d + 2d (mastery). answer-window addition. 1. Fill tens86 + 47Step 1: Fill tens86plus4712raw windows8 + 4 = 12 then keep 2; carry waitsrunning strip12Tens window: 8 + 4 = 12. Hold raw 12; carry settles later.2. Fill onesStep 2: Fill ones86plus471213raw windows6 + 7 = 13 then keep 3; carry waitsrunning strip123Ones window: 6 + 7 = 13. Hold raw 13; settle carry later.3. Settle carryStep 3: Settle carryKeep ones; carry moves left.raw windows12 | 13settled digits1 | 3 | 3answer 133Settle raw 12 | 13 into 133; keep ones and move carry left.
