6,052 articles
42 (number)
42 (forty-two) is the natural number after 41, the product of 2, 3, and 7, and Douglas Adams's famous "Answer to Life, the Universe, and Everything."
43 (number)
43, or forty-three, is the natural number after 42: a prime and Heegner number that is the atomic number of technetium and the ASCII code for the plus sign.
46 (number)
46 (forty-six) is the even semiprime number, the product 2 × 23, best known as the chromosome count in a typical human cell and palladium's atomic number.
47 (number)
47 is a prime number, the fifteenth prime, best known as the atomic number of silver, the number of avenging ronin in Japan's Akō incident, and a Pomona College mascot.
5 (number)
5, written V in Roman numerals, is the third prime number, a Fibonacci number, and the hypotenuse of the smallest Pythagorean triple, 3, 4, 5.
50 (number)
50 (fifty) is the natural number following 49, written L in Roman numerals, the atomic number of tin, and the years in a Golden Jubilee.
55 (number)
55 (fifty-five) is the natural number after 54, notable as both the 10th triangular number and the 10th Fibonacci number, and as the atomic number of cesium.
57 (number)
57 (fifty-seven) is a composite number and squarefree semiprime, the product of the primes 3 and 19, widely known as the "Grothendieck prime" after an anecdote in which Alexandre Grothendieck suggested it as a prime.
6 (number)
6 is the natural number following 5 and preceding 7, the smallest perfect number, equal to 1 + 2 + 3, and also the third triangular number.
60 (number)
60 (sixty, Roman numeral LX) is the natural number following 59, best known as the base of the Babylonian sexagesimal system behind minutes, hours, and degrees.
600-cell
The 600-cell, also called the hexacosichoron, is the convex regular 4-polytope, the four-dimensional analog of the icosahedron, bounded by 600 tetrahedral cells, 1200 triangular faces, 720 edges, and 120 vertices.
666 (number)
666, also six hundred sixty-six and written DCLXVI in Roman numerals, is the number of the beast in Revelation 13:18, widely associated with Nero Caesar.
68–95–99.7 rule
The 68–95–99.7 rule, also called the empirical rule, states that for a normal distribution about 68%, 95%, and 99.7% of values lie within 1, 2, and 3 standard deviations of the mean.
69 (number)
69 (sixty-nine) is an odd semiprime, the product of the primes 3 and 23, known as the atomic number of thulium and, in slang, as a sex position.
7 (number)
7, or seven, is the fourth prime number and the second Mersenne prime, best known for underpinning the seven-day week and George A. Miller's 1956 memory paper.
70 (number)
70 (seventy) is a natural number with prime factorization 2 × 5 × 7, best known as the smallest weird number and the atomic number of ytterbium.
73 (number)
73, or seventy-three, is the 21st prime number that Sheldon Cooper called the best number on The Big Bang Theory; it is also the atomic number of tantalum.
777 (number)
777 is the natural number following 776, best known as the triple-seven jackpot symbol on slot machines and a sphenic, palindromic, Harshad number in number theory.
786 (number)
786 is an even composite number whose prime factorization is 2 × 3 × 131, known culturally as the Abjad value of the Bismillah in South Asia.
8 (number)
8 (eight), the natural number following 7 and preceding 9, is the cube of 2, the sixth Fibonacci number, and the number of bits in a byte.
80 (number)
80 is the natural number following 79, a composite abundant number with ten divisors, the atomic number of mercury, and the number French names quatre-vingts, four twenties.
88 (number)
88 (eighty-eight) is the natural number after 87, best known as the number of keys on a piano, the constellations recognized by the IAU, and radium's atomic number.
89 (number)
89, or eighty-nine, is the natural number after 88 and before 90. It is the 24th prime, the 11th Fibonacci number, and actinium's atomic number.
9 (number)
9 (nine) is the natural number following 8 and preceding 10: the largest single digit, the square of 3, and the smallest odd composite number, basis of casting out nines.
90 (number)
90 (ninety), the natural number following 89 and preceding 91, is an abundant pronic number with twelve divisors, best known as the degree measure of a right angle.
A History of Vector Analysis
A History of Vector Analysis is the history of how modern vector analysis, built from Hamilton's quaternions and Grassmann's extension theory, became the standard language of physics.
A New Kind of Science
A New Kind of Science is a 2002 book by Stephen Wolfram arguing that simple computer programs, rather than mathematical equations, are the right foundation for modeling nature.
A posteriori error estimation
A posteriori error estimation is a numerical analysis technique that estimates the error of a computed solution after the solve, using the solution itself to steer adaptive mesh refinement.
A/B testing
A/B testing, also called split testing or online controlled experiment, randomly assigns users to product variants so measured behavior differences can be attributed to the change tested.
A¹ homotopy theory
A¹ homotopy theory, also called motivic homotopy theory, is a homotopy theory for algebraic geometry developed by Fabien Morel and Vladimir Voevodsky in the 1990s.