Wikipedia:Articles for deletion/Determination of the day of the week
basically per what Mark viking said. The whole field of algorithms is "how to"; that doesn't make descriptions of notable algorithmic problems off-topic for Wikipedia.  is misapplied in this case: it's more aimed at keeping out game walkthroughs, troubleshooting guides, and recipes than descriptions of mathematical algorithms. And in this case, the attention to this specific problem given by such famous mathematicians as Charles Dodgson and John Conway makes it clearly notable
— User:David, 23:04, 18 December 2012 (UTC)
Stance: keep
Cited policy: WP:NOTHOWTO (Wikipedia:What Wikipedia is not)