number of unique digits in a positional numeral system
for other uses, see
radix (disambiguation).
numeral systems 


hindu–arabic numeral system 

 western arabic
 eastern arabic
 bengali
 devanagari
 gujarati
 gurmukhi
 sinhala
 tamil
 balinese
 burmese
 dzongkha
 javanese
 khmer
 lao
 mongolian
 thai

east asian 

 chinese
 hokkien
 japanese
 korean
 vietnamese
 tangut

alphabetic 

 abjad
 armenian
 Āryabhaṭa
 cyrillic
 ge'ez
 georgian
 greek
 hebrew
 roman

former 

 aegean
 attic
 babylonian
 brahmi
 chuvash
 egyptian
 etruscan
 glagolitic
 inuit
 kharosthi
 mayan
 muisca
 quipu

base 

 2
 3
 4
 5
 6
 8
 10
 12
 16
 20
 60

nonstandard positional numeral systems 

 bijective numeration (1)
 signeddigit representation (balanced ternary)
 mixed (factorial)
 negative
 complexbase system (2i)
 noninteger representation (φ)
 asymmetric numeral systems

list of numeral systems 

in digital numeral systems, the radix or base is the number of unique digits, including the digit zero, used to represent numbers in a positional numeral system. for example, for the decimal/denary system (the most common system in use today) the radix (base number) is ten, because it uses the ten digits from 0 through 9.
in any standard positional numeral system, a number is conventionally written as (x)_{y} with x as the string of digits and y as its base, although for base ten the subscript is usually assumed (and omitted, together with the pair of parentheses), as it is the most common way to express value. for example, (100)_{10} is equivalent to 100 (the decimal system is implied in the latter) and represents the number one hundred, while (100)_{2} (in the binary system with base 2) represents the number four.^{[1]}