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Nonpositional numeral systems

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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).[1] 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.


  1. 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).