Hi, as a beginner I have checked a few solutions and learned about:

• isdigit() - True for all Base 10 Numbers, Fractions ('⅔') and Superscripts ('2²')
• isnumeric() - True for all Base 10 Numbers, Fractions ('⅔'), Superscripts ('2²')and Roman Numerals ('ↁ')
• isdecimal() - True for all Base 10 Numbers

In the test strings Fractions ('⅔'), Superscripts ('2²')and Roman Numerals ('ↁ') are not handled. Is that wanted? I guess not as we should count the number of digits, that meant 0-9 numbers, correct?

Maybe a few other test cases should be added.