> The input "01" fails all the other solutions as well. You can't divide or take the log of a string. The other solutions fail differently - they generates an

> The input "01" fails all the other solutions as well. You can't divide or take the log of a string. The other solutions fail differently - they generates an error and stop processing. The `len(str())` failure doesn't generate an error, and doesn't stop processing, it simply returns the wrong answer. So, the `len` approach is wrong, the other approaches are right.