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Recreational Mathematics Magazine

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Finding the Year’s Share in Day-of-Week Calculations

S. Kamal Abdali
Published Online: 2016-12-08 | DOI: https://doi.org/10.1515/rmm-2016-0008


The dominant part in the mental calculation of the day of the week for any given date is to determine the year share, that is, the contribution of the two-digit year part of the date. This paper describes a number of year share computation methods, some well-known and some new. The “Parity Minus 3” method, in particular, is a new alternative to the popular “Odd+11” method. The paper categorizes the methods of year share computation, and presents simpler proofs of their correctness than usually provided.

Keywords: day of the week; calendar algorithms; doomsday method; first Sunday algorithm; mental arithmetic; year share


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About the article

Published Online: 2016-12-08

Published in Print: 2016-12-01

Citation Information: Recreational Mathematics Magazine, Volume 3, Issue 6, Pages 75–86, ISSN (Online) 2182-1976, DOI: https://doi.org/10.1515/rmm-2016-0008.

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© 2016. This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License. BY-NC-ND 4.0

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