Numerical digits are the number text characters used to show numerals. For example, the numeral "56" has two digits: 5 and 6. In the decimal system (which is base 10), each digit is how many of a certain power of 10 are needed to get the value. The rightmost, or units digit, is for 10^0, the next digit is for 10^1, etc.

The numeral "56" means:  6*10^0 + 5*10^1 = 6*1 + 5*10 = 6 + 50.