Nonpositional numeral systems
Nonpositional numeral systems or non place-value systems of numeration are systems of numeration in which the placement of a numeral digit does not change its value.
In Roman numerals, for example, the symbol V always means "five" whether it occurs last in a numeral string (e.g., XXV), next to last (XXVI), third from last (XXVII) or fourth from last (XXVIII). By contrast the symbol 5 in base 10 can mean "five," "fifty," "five hundred," etc., (as well as "fifth," "fiftieth" and so on) depending on its placement in the numeral string.
- Though of course the Roman numeral system made some fitful and haphazard progress towards becoming a positional system, first of all in the sorting of symbols from greatest to least, and also in the subtraction of symbols, such as the symbol I in IV or IX is subtracted from the next symbol (same for X in XL or XC, C in CD or CM).