Oct 21 - Eye of Horus and Unit Fractions

 In Ancient Egypt the Eye of Horus was seen as a symbol of protection. The symbol originates from a myth describing a battle between Horus and Set, after Set killed Osiris (Horus' father). In the myth Horus has his eye gouged out and shattered, and later another god, Thoth, restores it.

Each of the hieroglyphs that comprise it represent a unit fraction with denominators of powers of two. Doing so allowed the Eye to be used as a tool for measuring grain. 

Numbers that come to mind immediately as being special are 3, 7 and 13. I don't know the origins but I know 3 is a mystical number, 7 is lucky, and 13 is unlucky. I also find it interesting that western culture puts increased significance on anniversaries in multiples of 5.

http://www.maths.surrey.ac.uk/hosted-sites/R.Knott/Fractions/egyptian.html

https://en.wikipedia.org/wiki/Eye_of_Horus

https://en.wikipedia.org/wiki/Egyptian_fraction

https://www.greatscott.com/lessons/eye-of-horus-fractions/

https://3010tangents.wordpress.com/2015/02/23/egyptian-fractions-from-mythology-to-computation/