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Addition

Level 21 / mastery

4d + 3d (no carry)

5 visual steps / large answer-window addition

1. Fill thousands

Step 1: Fill thousands
raw windows
running strip
Thousands window: 2 + 0 = 2. Release 2.

Thousands window: 2 + 0 = 2. Release 2.

2. Fill hundreds

Step 2: Fill hundreds
raw windows
running strip
Hundreds window: 4 + 5 = 9. Release 9.

Hundreds window: 4 + 5 = 9. Release 9.

3. Fill tens

Step 3: Fill tens
raw windows
running strip
Tens window: 3 + 2 = 5. Release 5.

Tens window: 3 + 2 = 5. Release 5.

4. Fill ones

Step 4: Fill ones
raw windows
running strip
Ones window: 1 + 6 = 7. Release 7.

Ones window: 1 + 6 = 7. Release 7.

5. Read answer

Step 5: Read answer
Settle onceThe visible windows already read left to right.raw windows
settled digits
Read 2957; estimate before submit.

Read 2957; estimate before submit.

Practice Level 21

A few quick rounds make digit release automatic; carry is the only thing to keep.

Start Level