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Math Gym
Subtraction Guide

Subtraction Level 18: 3d - 3d (cascade borrow). borrow-window subtraction.

1. Release hundreds

1. Release hundredsRelease one digit; only borrow stays active.
answer strip
Pay right borrow; release 5: 7 - 1 - 1 = 5.

2. Release tens

2. Release tens
answer strip
Borrow 10; pay right borrow: 16 - 8 - 1 = 7.

3. Release ones

3. Release ones
answer strip
Borrow 10; release 5: 12 - 7 = 5.

4. Read answer

4. Read answerDrop finished digits; borrow is gone.
Read 5 | 7 | 5 as 575; borrow is gone.