al-haytham
71Number theory — A Lehmer sieve an analog computer once used for finding primes and solving simple diophantine equations. Number theory is a branch of pure mathematics devoted primarily to the study of the integers. Number theorists study prime numbers (the… …
72Perfect number — In number theory, a perfect number is a positive integer that is equal to the sum of its proper positive divisors, that is, the sum of its positive divisors excluding the number itself (also known as its aliquot sum). Equivalently, a perfect… …
73Scientific Revolution — The period which many historians of science call the Scientific Revolution can be roughly dated as having begun in 1543, the year in which Nicolaus Copernicus published his De revolutionibus orbium coelestium (On the Revolutions of the Heavenly… …
74Vacuum — This article is about empty physical space or the absence of matter. For other uses, see Vacuum (disambiguation). Free space redirects here. For other uses, see Free space (disambiguation). Pump to demonstrate vacuum In everyday usage, vacuum is… …
751000 — The year 1000 of the Gregorian Calendar was the last year of the 10th century as well as the last year of the first millennium of the Christian era ending on December 31st. According to the then used Julian Calendar, AD 1000 was a leap year… …
76Wilson's theorem — In mathematics, Wilson s theorem states that a natural number n > 1 is a prime number if and only if (see factorial and modular arithmetic for the notation). Contents 1 History 2 Proofs …
77Visual perception — In psychology, visual perception is the ability to interpret information from visible light reaching the eyes. The resulting perception is also known as eyesight, sight or vision. The various physiological components involved in vision are… …
78Visual system — The visual system includes the eyes, the connecting pathways through to the visual cortex and other parts of the brain. The illustration shows the mammalian system. The visual system is the part of the central nervous system which enables… …
79Al-Andalus — This article is about the historical region. For the modern day region, see Andalusia. For the district in Kuwait, see Kuwait City. For the musical group, see Andalus. History of Al Andalus 711–1492 711–732 Musl …
80Perspective (graphical) — Part of a series on …
