Unary numeral system
Overview
 
The unary numeral system is the bijective base-1 numeral system
Numeral system
A numeral system is a writing system for expressing numbers, that is a mathematical notation for representing numbers of a given set, using graphemes or symbols in a consistent manner....

. It is the simplest numeral system
Numeral system
A numeral system is a writing system for expressing numbers, that is a mathematical notation for representing numbers of a given set, using graphemes or symbols in a consistent manner....

 to represent natural number
Natural number
In mathematics, the natural numbers are the ordinary whole numbers used for counting and ordering . These purposes are related to the linguistic notions of cardinal and ordinal numbers, respectively...

s: in order to represent a number N, an arbitrarily chosen symbol representing 1 is repeated N times. For example, using the symbol | (a tally mark), the number 6 is represented as ||||||.
 
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