“Number is limited multitude or a combination of units or a flow of quantity made up of units; and the first division of number is even and odd.”
Context: Nicomachus of Gerasa: Introduction to Arithmetic (1926), Book I, Chapter VII
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Nicomachus 22
Ancient Greek mathematician 60–120Related quotes

“A prime number is one (which is) measured by a unit alone.”
Elements, Book 7, Definition 11 (12 in certain editions)
Euclid’s Elements

Zero can never be a unit.
Definition 3. Part 1. The Elementary Conjunctions of Extensive Magnitudes. Ch. 1. Addition, Subtraction, Multiples and Fractions of Extensive Magnitudes. 1. Concepts and laws of calculation. Extension Theory Hermann Grassman, History of Mathematics (2000) Vol. 19 Tr. Lloyd C. Kannenberg, American Mathematical Society, London Mathematical Society
Ausdehnungslehre (1844)
“Number is different from quantity.”
Source: Mind and Nature, a necessary unity, 1988, p. 118
Source: Living systems, 1978, p. 16; As cited in: Sven Rasegård (2002) Man and Science: A Web of Systems and Social Conventions. p. 29

“You have to be odd to be number one”

“It is not of the essence of mathematics to be conversant with the ideas of number and quantity.”
Source: 1850s, An Investigation of the Laws of Thought (1854), p. 12; Cited in: Alexander Bain (1870) Logic, p. 191

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Introduction to the Analysis of the Infinite (1748)
100 Years of Mathematics: a Personal Viewpoint (1981)