A numeral system (or system of numeration) is a writing system for expressing numbers; that is, a mathematical notation for representing numbers of a given set, using digits or other symbols in a consistent manner.. The same sequence of symbols may represent different numbers in different numeral systems. For example, "11" represents the number eleven in the decimal …

The unary numeral system is the simplest numeral system to represent natural numbers: to represent a number N, a symbol representing 1 is repeated N times. [2] In the unary system, the number 0 (zero) is represented by the empty string , that is, the absence of a symbol.

Greek numerals are a system of representing numbers using letters of the Greek alphabet.They are also known by the names Milesian numerals, Alexandrian numerals, or alphabetic numerals.In modern Greece, they are still in use for ordinal numbers, and in much of the same way that Roman numerals are in the West; for ordinary numbers, Arabic numerals are used.