repdigitとは 意味・読み方・使い方

語源

Blend of rep(eated) +‎ digit.

発音

• (Received Pronunciation, General American) IPA: /ˈɹɛpˌdɪd͡ʒɪt/
• ハイフネーション: rep‧di‧git

名詞

repdigit (plural repdigits)

1. (recreational mathematics) A number composed only of one or more occurrences of one specific digit and no other digit.
   • 1975, David W. Ballew, Ronald C. Weger, “Repdigit Triangular Numbers”, in Journal of Recreational Mathematics, volume 8, number 2, Farmingdale, N.Y.: Baywood Publishing Co., →ISSN, →OCLC, pages 96–98:

     Repdigit Triangular Numbers [article title]

   • 1980 January, Murray S[eymour] Klamkin, quoting Charles W. Trigg, “The Olympiad Corner: 11”, in Crux Mathematicorum, volume 6, number 1, Ottawa, Ont.: Canadian Mathematical Society, →ISSN, →OCLC, page 16:

     Is there any system of notation in which there is a repdigit ${\displaystyle aa}$ such that ${\displaystyle (aa)^{2}=ccdd}$, with ${\displaystyle c=a-1}$ and ${\displaystyle d=c-1}$?

   • 2002, Clifford A[lan] Pickover, “Gallery I: Squares, Cubes, and Tesseracts”, in The Zen of Magic Squares, Circles, and Stars: An Exhibition of Surprising Structures across Dimensions, Princeton, N.J.; Woodstock, Oxfordshire: Princeton University Press, →ISBN, page 284:

     Here is another palindromic magic square that has the added property of having main diagonals containing eight repeating "repdigits": 222, 333, 444, 555, 666, 777, 888, and 999. The magic sum is 2442.

   • 2005, James J[oseph] Tattersall, “Modular Arithmetic”, in Elementary Number Theory in Nine Chapters, 2nd edition, Cambridge: Cambridge University Press, →ISBN, section 5.6 (Supplementary Exercises), paragraph 14, page 193:

     A positive with repeated digit is called a repdigit, for example 222, 55555, and all repunits are repdigits.

下位語

• repunit

参考

• repeating decimal
• repetend

参照

• Eric W[olfram] Weisstein (20 August 2018 (last accessed)), “Repdigit”, in MathWorld‎, archived from the original on 15 February 2018.

Further reading

• repdigit on Wikipedia.Wikipedia