📜 WAYPOINT LESSON
Checkpoint: digital root
⭐⭐⭐ advanced⏳ 20 min read📍 Lesson 200 of 256
Two recursive layers: digit sum inside, self-recursion outside.
The digital root is recursion composed with recursion: an inner helper consumes digits while an outer process consumes the results. Both base cases are visible in the example trace — find them before writing anything.