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{{Short description|Number of digits of a numeral system}}{{other uses}}{{Numeral systems|expand=Place-value notation|expand2=By radix/base}}In a positional numeral system, the radix ({{plural form}}: radices) or base is the number of unique digits, including the digit zero, used to represent numbers. For example, for the decimal system (the most common system in use today) the radix is ten, because it uses the ten digits from 0 through 9.In any standard positional numeral system, a number is conventionally written as {{nowrap|(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.

Etymology

(:wikt:radix|Radix) is a Latin word for "root". Root can be considered a synonym for base, in the arithmetical sense.

In numeral systems

Generally, in a system with radix b ({{nowrap|b > 1}}), a string of digits {{nowrap|d1 ... dn}} denotes the number {{nowrap|d1b'n−1 + d2b'n−2 + … + dnb0}}, where {{nowrap|0 ≤ di < b}}.BOOK , In contrast to decimal, or radix 10, which has a ones' place, tens' place, hundreds' place, and so on, radix b would have a ones' place, then a b1s' place, a b2s' place, etc.WEB,weblink Binary, experimonkey.com, 2023-05-14, For example, consider the system with radix 12. In this system, a string of digits such as 59A (where the letter "A" represents the value of ten) would represent the value {{nowrap|5 × 12'2 + 9 × 12'1 + 10 × 120}} = 838 in base 10.Commonly used numeral systems include:{| class="wikitable sortable"! Base/radix! Name! Description| 2| Binary numeral system

computers. The two digits are "0" and "1", expressed from switches displaying OFF and ON, respectively. Used in most electric counter (digital)>counters.

| 8

Octal>Octal system| Used occasionally in computing. The eight digits are "0"–"7" and represent 3 bits (23).

| 10

Decimal>Decimal system| Used by humans in the vast majority of cultures. Its ten digits are "0"–"9". Used in most mechanical counters.

| 12

Duodecimal>Duodecimal (dozenal) system	dozens and gross (unit)>grosses.

| 16

Hexadecimal>Hexadecimal system| Often used in computing as a more compact representation of binary (1 hex digit per 4 bits). The sixteen digits are "0"–"9" followed by "A"–"F" or "a"–"f".

| 20

Vigesimal>Vigesimal system	score (number)>score system in English, now most famous in the phrase "four score and seven years ago" in the Gettysburg Address.

| 60

Sexagesimal>Sexagesimal system| Originally used in modified form in ancient Sumer and passed to the Babylonians. BOOK , Bertman, Stephen , Handbook to Life in Ancient Mesopotamia , 2005, Oxford Univ. Press , Oxford [u.a.] , 978-019-518364-1 , 257 , Paperback ,weblink , Used today as the basis of modern circular coordinate system (degrees, minutes, and seconds) and time measuring (minutes, and seconds) by analogy to the rotation of the Earth.

{{for|a larger list|List of numeral systems}}The octal and hexadecimal systems are often used in computing because of their ease as shorthand for binary. Every hexadecimal digit corresponds to a sequence of four binary digits, since sixteen is the fourth power of two; for example, hexadecimal 7816 is binary {{gaps|111|1000}}2. Similarly, every octal digit corresponds to a unique sequence of three binary digits, since eight is the cube of two.This representation is unique. Let b be a positive integer greater than 1. Then every positive integer a can be expressed uniquely in the form where m is a nonnegative integer and the r's are integers such that Radices are usually natural numbers. However, other positional systems are possible, for example, golden ratio base (whose radix is a non-integer algebraic number),JOURNAL JOURNAL A negative base allows the representation of negative numbers without the use of a minus sign. For example, let b = −10. Then a string of digits such as 19 denotes the (decimal) number {{nowrap|1 × (−10)1 + 9 × (−10)0}} = −1.

See also

• Base (exponentiation)
• Mixed radix
• Polynomial
• Radix economy
• Radix sort
• Non-standard positional numeral systems

Notes

{{reflist|30em}}

References

External links

{{wiktionary|radix}}

• MathWorld entry on base