> 𝑛 will always be less than the number of digits of 𝑛, and ≥ 1 if you're using 1-indexing.
Consider `2.68` when 0-indexing. It's less than the number of digits of n, but ceil(2.68) isn't a valid index. Similarly `3.68` for 1-indexing.
I would change this to something like
> If you choose `0` indexing, n will be >= 0 and ceil(n) will be < the number of digits of n.
> If you choose `1` indexing, n will be > 0 and ceil(n) will be <= the number of digits of n.