I think the OP made the mistake of trying to solve the problem directly, and when he got errors, he got nervous which made him get more errors. Instead the right strategy would be to think aloud "well, how do I get the digits of a number? first, cast the number into a string then try to see if I can treat it as a list. Ok, let's try (seq (str 10)) on the repl....". Having an instant feedback and being able to no exactly if a small instruction works or not would have helped him to focus better, and avoid nervousness.