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Quinary (base-5 or pental^{[1]}^{[2]}^{[3]}) is a numeral system with five as the base. A possible origination of a quinary system is that there are five fingers on either hand.
In the quinary place system, five numerals, from 0 to 4, are used to represent any real number. According to this method, five is written as 10, twenty-five is written as 100 and sixty is written as 220.
As five is a prime number, only the reciprocals of the powers of five terminate, although its location between two highly composite numbers (4 and 6) guarantees that many recurring fractions have relatively short periods.
Today, the main usage of base 5 is as a biquinary system, which is decimal using five as a sub-base. Another example of a sub-base system, is sexagesimal, base 60, which used 10 as a sub-base.
Each quinary digit has log_{2}5 (approx. 2.32) bits of information.^{[4]}
Few calculators support calculations in the quinary system, except for some Sharp models (including some of the EL-500W and EL-500X series, where it is named the pental system^{[1]}^{[2]}^{[3]}) since about 2005, as well as the open-source scientific calculator WP 34S. The Python programming language supports conversion of a string to quinary using the int function. For example, if s='101' then the function print(int('101',5)) would return 26.^{[5]}
× | 1 | 2 | 3 | 4 | 10 | 11 | 12 | 13 | 14 | 20 |
1 | 1 | 2 | 3 | 4 | 10 | 11 | 12 | 13 | 14 | 20 |
2 | 2 | 4 | 11 | 13 | 20 | 22 | 24 | 31 | 33 | 40 |
3 | 3 | 11 | 14 | 22 | 30 | 33 | 41 | 44 | 102 | 110 |
4 | 4 | 13 | 22 | 31 | 40 | 44 | 103 | 112 | 121 | 130 |
10 | 10 | 20 | 30 | 40 | 100 | 110 | 120 | 130 | 140 | 200 |
11 | 11 | 22 | 33 | 44 | 110 | 121 | 132 | 143 | 204 | 220 |
12 | 12 | 24 | 41 | 103 | 120 | 132 | 144 | 211 | 223 | 240 |
13 | 13 | 31 | 44 | 112 | 130 | 143 | 211 | 224 | 242 | 310 |
14 | 14 | 33 | 102 | 121 | 140 | 204 | 223 | 242 | 311 | 330 |
20 | 20 | 40 | 110 | 130 | 200 | 220 | 240 | 310 | 330 | 400 |
Quinary | 0 | 1 | 2 | 3 | 4 | 10 | 11 | 12 | 13 | 14 | 20 | 21 | 22 |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Binary | 0 | 1 | 10 | 11 | 100 | 101 | 110 | 111 | 1000 | 1001 | 1010 | 1011 | 1100 |
Decimal | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
Quinary | 23 | 24 | 30 | 31 | 32 | 33 | 34 | 40 | 41 | 42 | 43 | 44 | 100 |
Binary | 1101 | 1110 | 1111 | 10000 | 10001 | 10010 | 10011 | 10100 | 10101 | 10110 | 10111 | 11000 | 11001 |
Decimal | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 |
Decimal (periodic part) | Quinary (periodic part) | Binary (periodic part) |
1/2 = 0.5 | 1/2 = 0.2 | 1/10 = 0.1 |
1/3 = 0.3 | 1/3 = 0.13 | 1/11 = 0.01 |
1/4 = 0.25 | 1/4 = 0.1 | 1/100 = 0.01 |
1/5 = 0.2 | 1/10 = 0.1 | 1/101 = 0.0011 |
1/6 = 0.16 | 1/11 = 0.04 | 1/110 = 0.010 |
1/7 = 0.142857 | 1/12 = 0.032412 | 1/111 = 0.001 |
1/8 = 0.125 | 1/13 = 0.03 | 1/1000 = 0.001 |
1/9 = 0.1 | 1/14 = 0.023421 | 1/1001 = 0.000111 |
1/10 = 0.1 | 1/20 = 0.02 | 1/1010 = 0.00011 |
1/11 = 0.09 | 1/21 = 0.02114 | 1/1011 = 0.0001011101 |
1/12 = 0.083 | 1/22 = 0.02 | 1/1100 = 0.0001 |
1/13 = 0.076923 | 1/23 = 0.0143 | 1/1101 = 0.000100111011 |
1/14 = 0.0714285 | 1/24 = 0.013431 | 1/1110 = 0.0001 |
1/15 = 0.06 | 1/30 = 0.013 | 1/1111 = 0.0001 |
1/16 = 0.0625 | 1/31 = 0.0124 | 1/10000 = 0.0001 |
1/17 = 0.0588235294117647 | 1/32 = 0.0121340243231042 | 1/10001 = 0.00001111 |
1/18 = 0.05 | 1/33 = 0.011433 | 1/10010 = 0.0000111 |
1/19 = 0.052631578947368421 | 1/34 = 0.011242141 | 1/10011 = 0.000011010111100101 |
1/20 = 0.05 | 1/40 = 0.01 | 1/10100 = 0.000011 |
1/21 = 0.047619 | 1/41 = 0.010434 | 1/10101 = 0.000011 |
1/22 = 0.045 | 1/42 = 0.01032 | 1/10110 = 0.00001011101 |
1/23 = 0.0434782608695652173913 | 1/43 = 0.0102041332143424031123 | 1/10111 = 0.00001011001 |
1/24 = 0.0416 | 1/44 = 0.01 | 1/11000 = 0.00001 |
1/25 = 0.04 | 1/100 = 0.01 | 1/11001 = 0.00001010001111010111 |
Many languages^{[6]} use quinary number systems, including Gumatj, Nunggubuyu,^{[7]} Kuurn Kopan Noot,^{[8]} Luiseño^{[9]} and Saraveca. Gumatj is a true "5–25" language, in which 25 is the higher group of 5. The Gumatj numerals are shown below:^{[7]}
Number | Base 5 | Numeral |
---|---|---|
1 | 1 | wanggany |
2 | 2 | marrma |
3 | 3 | lurrkun |
4 | 4 | dambumiriw |
5 | 10 | wanggany rulu |
10 | 20 | marrma rulu |
15 | 30 | lurrkun rulu |
20 | 40 | dambumiriw rulu |
25 | 100 | dambumirri rulu |
50 | 200 | marrma dambumirri rulu |
75 | 300 | lurrkun dambumirri rulu |
100 | 400 | dambumiriw dambumirri rulu |
125 | 1000 | dambumirri dambumirri rulu |
625 | 10000 | dambumirri dambumirri dambumirri rulu |
In the video game Riven and subsequent games of the Myst franchise, the D'ni language uses a quinary numeral system.
A decimal system with 2 and 5 as a sub-bases is called biquinary, and is found in Wolof and Khmer. Roman numerals are a biquinary system. The numbers 1, 5, 10, and 50 are written as I, V, X, and L respectively. Eight is VIII and seventy is LXX.
Most versions of the abacus use a biquinary system to simulate a decimal system for ease of calculation. Urnfield culture numerals and some tally mark systems are also biquinary. Units of currencies are commonly partially or wholly biquinary.
A vigesimal system with 4 and 5 as a sub-bases is found in Nahuatl, Kaktovik Inupiaq numerals and the Maya numerals.