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Math Gym
Subtraction Guide

Subtraction Level 20: 3d - 3d (mastery). borrow-window subtraction.

1. Release hundreds

1. Release hundredsRelease one digit; only borrow stays active.
answer strip
Pay right borrow; release 4: 9 - 4 - 1 = 4.

2. Release tens

2. Release tens
answer strip
Borrow 10; pay right borrow: 10 - 6 - 1 = 3.

3. Release ones

3. Release ones
answer strip
Borrow 10; release 7: 15 - 8 = 7.

4. Read answer

4. Read answerDrop finished digits; borrow is gone.
Read 4 | 3 | 7 as 437; borrow is gone.