Status: IN
Digit extraction, digit checking, and popcount operations consistently use string conversion (str(), indexing, character iteration, bin().count()) rather than modular arithmetic across unrelated problems.
String conversion is the universal digit-decomposition idiom, chosen for readability over performance
Depends on (SL): str-conversion-digit-extraction-idiom, string-based-digit-check-idiom, digit-sum-via-str-conversion, bin-count-for-popcount