HAVING hit upon the following method of mentally computing the day of the week for any given date, I send it you in the hope that it may interest some of your readers. I am not a rapid computer myself, and as I find my average time for doing any such question is about 20 seconds, I have little doubt that a rapid computer would not need 15.
About this article
The Mathematical Gazette (2019)
Do calendrical savants use calculation to answer date questions? A functional magnetic resonance imaging study
Philosophical Transactions of the Royal Society B: Biological Sciences (2009)
Infancia y Aprendizaje (2001)