IDEAS home Printed from https://ideas.repec.org/a/sdb/social/v8y2019i1p66-76.html
   My bibliography  Save this article

The Extended Sum of the Digits of a Natural Number in the Ddecimal Representation "The Test With 9" and Fermat's Diagnosis

Author

Listed:
  • Tatiana Dosescu

    (Dimitrie Cantemir Christian University)

Abstract

This note presents a justification of the well-known procedure called "the test with 9" to verify the correctness of some sums or multiplications with natural numbers. The diagnosis of a 12-digit number that was non-prime, was quickly established by Fermat in the 17th century. To verify this result was used "the test with 9".

Suggested Citation

  • Tatiana Dosescu, 2019. "The Extended Sum of the Digits of a Natural Number in the Ddecimal Representation "The Test With 9" and Fermat's Diagnosis," Social-Economic Debates, Association for Entreprenorial Spirit Promotion, vol. 8(1), pages 66-76, April.
    • Handle: RePEc:sdb:social:v:8:y:2019:i:1:p:66-76
    as

    Download full text from publisher

    File URL: http://www.economic-debates.ro/art%208%20DSE%201%202019%20Dosescu.pdf
    Download Restriction: no
    File URL: http://www.economic-debates.ro/art%208%20DSE%201%202019%20Dosescu.pdf
    Download Restriction: no
    ---><---

    More about this item

    Keywords

    Algebraic structures: group; unitary commutative ring; the grammar of a language; the divisibility criterion with 9 in N; the relation of congruence;
    All these keywords.

    JEL classification:

    • C12 - Mathematical and Quantitative Methods - - Econometric and Statistical Methods and Methodology: General - - - Hypothesis Testing: General
    • C14 - Mathematical and Quantitative Methods - - Econometric and Statistical Methods and Methodology: General - - - Semiparametric and Nonparametric Methods: General

    Statistics

    Access and download statistics

    Corrections

    All material on this site has been provided by the respective publishers and authors. You can help correct errors and omissions. When requesting a correction, please mention this item's handle: RePEc:sdb:social:v:8:y:2019:i:1:p:66-76. See general information about how to correct material in RePEc.

    If you have authored this item and are not yet registered with RePEc, we encourage you to do it here. This allows to link your profile to this item. It also allows you to accept potential citations to this item that we are uncertain about.

    We have no bibliographic references for this item. You can help adding them by using this form .

    If you know of missing items citing this one, you can help us creating those links by adding the relevant references in the same way as above, for each refering item. If you are a registered author of this item, you may also want to check the "citations" tab in your RePEc Author Service profile, as there may be some citations waiting for confirmation.

    For technical questions regarding this item, or to correct its authors, title, abstract, bibliographic or download information, contact: Adi Sava (email available below). General contact details of provider: http://www.economic-debates.ro/ .

    Please note that corrections may take a couple of weeks to filter through the various RePEc services.

    IDEAS is a RePEc service. RePEc uses bibliographic data supplied by the respective publishers.