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Subtraction

Level 18 / realistic untimed

3d - 3d (cascade borrow)

4 visual steps / 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.

Pay right borrow; release 5: 7 - 1 - 1 = 5.

2. Release tens

2. Release tensRelease one digit; only borrow stays active.
answer strip
Borrow 10; pay right borrow: 16 - 8 - 1 = 7.

Borrow 10; pay right borrow: 16 - 8 - 1 = 7.

3. Release ones

3. Release onesRelease one digit; only borrow stays active.
answer strip
Borrow 10; release 5: 12 - 7 = 5.

Borrow 10; release 5: 12 - 7 = 5.

4. Read answer

4. Read answerRelease one digit; only borrow stays active.Read answerDrop finished digits; borrow is gone.
Read 5 | 7 | 5 as 575; borrow is gone.

Read 5 | 7 | 5 as 575; borrow is gone.

Practice Level 18

A few quick rounds make each dropped digit feel light; borrow is the only thing to keep.

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