Give an example of a positional number system.

Positional systems are such systems as decimal, binary, octal, hexadecimal, etc. and not a positional number is the Roman numeral system, if in the decimal system we take the number 100, then the first number on the right means units, the second tens, and the third hundreds, and in Roman, for example, the number xxx that is 30, all three numbers mean the number 10 and adding them up we we get 30 in this and the difference between these systems.