1. Left Edge
4x5 = 20. Carry waits for settle.
4d x 4d (medium th)
6 visual steps / multi-digit window train
2. 2-Pair Window
2 pairs: 4x3 + 2x5 = 22. Carry waits for settle.
3. 3-Pair Window
3 pairs: 4x2 + 2x3 + 1x5 = 19. Carry waits for settle.
4. 4-Pair Center
4 pairs = 26. Carry waits for settle.
5. 3-Pair Right Window
3 pairs: 2x1 + 1x2 + 3x3 = 13. Carry waits for settle.
6. Settle strip
20 | 22 | 19 | 26 | 13 | 7 | 3 -> 22417373.
Practice Level 28
A few quick rounds make the train automatic; each raw window keeps one digit.
Start Level