| |
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| 3 | |
|---|---|
| Cardinal | Three |
| Ordinal | Third |
| Numeral system | ternary system |
| Factorization | (prime number) |
| Roman numeral | III |
| Binary | 011 |
| Hexadecimal | 03 |
| Table of contents |
|
2 Three-ness in human culture 3 Groups of three 4 Other fields |
Mathematics
Three is the second smallest prime number (after two), and the only one divisible by three; the next prime number is five. Three is the first Fermat prime (221 + 1) as well as the first Mersenne prime (22 - 1). It is also a factorial prime (2! + 1).
Three is the second triangular number.
Three is a Fibonacci number (And it is the third different one, too!). It is also a Lucas number.
Fractions with 3 in the denominator have a single digit repeating sequences in their decimal expansions, (.000…, .333… or .666…)
A natural number is divisible by three if the sum of its digits in base 10 is divisible by 3.
Three-ness in human culture
Many human cultures have given the concept of three-ness symbolic meanings. The Holy Trinity in Christian doctrine (or trinity in general), is God both a single entity and three entities, the Father, the Son and the Spirit.
The process of synthesis in Hegelianian dialectic creates three-ness from two-ness
The three Doshas (weaknesses) and their antidotes are the basis of Ayurvedic medicine in India. The three Gunas underlie action, in the Vedic system of knowledge. There is also the concept of Trimurti in Hindu tradition.
Three (三 pinyin san1) is considered a good number in Chinese culture because it sounds like the word "alive" (生 pinyin sheng1), compared to four.
Groups of three
Chemicals
Triacid, Triaminic, Triamcinolone, Triazine, Triazole, Tribromoethanol, Trichloroethylene, Trichlorfon, Trifluralin, Triglyceride, Triglycerophosphate, Triphosphopyridine nucleotide
Other fields