Elementary arithmetic, with brief notices of its history... by Robert Potts.

4 Hence it follows that all prime numbers, except 2 and 5, will end either with 1, 3, 7, or 9. Next, the number 3 being a prime number, every fourth number is divisible by 3, and may be omitted. Similarly, the number 7 being a prime number, every eighth number is divisible by 7, and may be omitted; and so on, omitting all numbers divisible by each of the successive prime numbers in order, until at length all the composite numbers are sifted out. Then the remaining numbers will be the prime numbers contained in the given series. As an exemplification of the process, let it be required to find all the prime numbers contained between the limits of 1 and 100. Having written down in order the first 100 numbers; first, 2 and and 5 are prime numbers; omitting 2 and 5, and all multiples of them, there will be found 31 of the numbers left. Next omitting 9, 21, 27, 33, 51, multiples of 3, a prime number; also 49, 77, 91, multiples of 7, a prime number. And the remaining numbers are11 19 31 43 59 71 83 13 23 37 47 61 73 89 17 29 41 53 67 79 97 and of these no one of the larger numbers is a multiple of any one of the smaller prime numbers; it follows that these must be prime numbers. And there are 25 or 26 (if unity be included) prime numbers in the first hundred of the natural numbers.' 1 The sieve of Eratosthenes was the name given to a contrivance he invented for finding the prime numbers. His method consisted in writing the natural numbers in order, beginning with unity, and continuing the series to any extent. He then separated or sifted out all numbers that were not prime numbers, and by this means he ascertained the prime numbers in the order of their magnitudes. The problem of finding in general a prime number, beyond a certain limit, by a direct process, has engaged the attention of mathematicians, but no results of a satisfactory nature have yet been attained. No algebraical formula has yet been discovered which will contain prime numbers only, as all known formula for prime numbers fail, including other numbers besides prime numbers. The cKdaKIos, or sieve, with some other fragments of the writings of Eratosthenes, was printed with the "Phsenomena of Aratus" at Oxford in 1672. Poetius, at the end of his Arithmetic, published at Leipsic in 1728, printed a table of the prime numbers and the factors of the composite numbers from 1 to 10,000. A similar table was published at Leyden by H. M. Anjema in 1767. A larger table, extending from 1 to 101,000, was published at Halle by M. Kruger, at the end of his "Thoughts on Algebra." Lambert extended this table as far as 102,000, and reprinted it, with other tables, at Berlin, in 1770. Peter Barlow, of the Royal Military Academy, published in 1814 a volume of Mathematical Tables. Table I. contains the prime numbers, and the factors of composite numbers from 1 to 10,000; also the reciprocals of these numbers calculated to ten places of decimals. It contains also the squares and cubes of these numbers with their square roots and cube roots each to seven places of decimals. Table V. is a register of all the prime numbers between 1 and 100,109.

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Title
Elementary arithmetic, with brief notices of its history... by Robert Potts.
Author
Potts, Robert, 1805-1885.
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Page 28
Publication
London,: Relfe bros.,
1876.
Subject terms
Arithmetic

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"Elementary arithmetic, with brief notices of its history... by Robert Potts." In the digital collection University of Michigan Historical Math Collection. https://name.umdl.umich.edu/abu7012.0001.001. University of Michigan Library Digital Collections. Accessed June 7, 2025.
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