Subtraction Level 10: 2d - 2d (mastery). borrow-window subtraction. 1. Release tens91 - 581. Release tensRelease one digit; only borrow stays active.91minus589 - 5 - 1 = 3answer strip3Pay right borrow; release 3: 9 - 5 - 1 = 3.2. Release ones2. Release ones91minus5811 - 8 = 3answer strip33Borrow 10; release 3: 11 - 8 = 3.3. Read answer3. Read answerDrop finished digits; borrow is gone.3 | 3 -> 33answer 33Read 3 | 3 as 33; borrow is gone.
