Navigation : AP CS Artificial Intelligence Intermediate CS - 3. Images - 7. Numbers - 8. Number Models - 13. Booleans - 15. Conditionals - 20. Using Structures - Sem.I Review - 21. Structures - 22a. Recursion -- 22a. Fibonacci -- 22a. Digits -- 22a. Sum Digits -- 22a. Fibsum -- 22a. More Recursion -- 22a. Harmonic -- 22a. Practice++ -- 22a. ss3 -- 22a. Recursive Helpers -- 22a. Recursion Quiz Practice -- 22a. Recursion Quiz 2018 -- 22a. Recursion Practice I 2019 -- Roygbiv Code -- 22a. Strings -- 22a. Helpers -- 22a. Helpers: Count Divisors -- 22a. Recursion Practice 3 -- 22a. Recursion Self Quiz -- 22a. Recursion Practice 4 -- 22a. Mini-Quiz -- 22a. Recursion Quiz 2 -- 22a. Recursion Practice 5 -- 22a. Recursion Practice 6 -- Quiz 3 (Hard) -- Quiz 4 (Medium) -- 22a. Hangman Project - 22b. Lists - Sem.II Review - Typed Racket - Resources - Pro Features - Online Help Robotics WY Robotics Exploring CS (Teachers) Resources 22a. Sum Digits sum-digits: whole-number -> number Find the sum of the digits in a number. n (sum-digits n) simplified 5 5 5 53 5 + 3 8 921 9 + 2 + 1 12 3216 3 + 2 + 1 + 6 12 65536 6 + 5 + 5 + 3 + 6 25 22a. Digits 22a. Fibsum