Addition Level 30: 4d + 4d (mastery). large answer-window addition. 1. Fill thousands7865 + 9287Step 1: Fill thousands7865plus928716raw windows7 + 9 = 16 then keep 6; carry waitsrunning strip16Thousands window: 7 + 9 = 16. Hold raw 16; carry settles later.2. Fill hundredsStep 2: Fill hundreds7865plus92871610raw windows8 + 2 = 10 then keep 0; carry waitsrunning strip160Hundreds window: 8 + 2 = 10. Hold raw 10; settle carry later.3. Fill tensStep 3: Fill tens7865plus9287161014raw windows6 + 8 = 14 then keep 4; carry waitsrunning strip1604Tens window: 6 + 8 = 14. Hold raw 14; settle carry later.4. Fill onesStep 4: Fill ones7865plus928716101412raw windows5 + 7 = 12 then keep 2; carry waitsrunning strip16042Ones window: 5 + 7 = 12. Hold raw 12; settle carry later.5. Settle carryStep 5: Settle carryKeep ones; carry moves left.raw windows16 | 10 | 14 | 12settled digits1 | 7 | 1 | 5 | 2answer 17152Settle raw 16 | 10 | 14 | 12 into 17152; keep ones and move carry left.