The Rule Of 13’s Level 2 – Bergie Web An unlucky number, a math equation and a way to encode or decipher messages. LINKS http://epgp.inflibnet.ac.in/epgpdata/uploads/epgp_content/S000005CH/P000667/M009114/ET/1455786849CHE__P12_M25_e-Text.pdf https://en.wikipedia.org/wiki/ROT13#:~:text=ROT13%20(%22rotate%20by%2013%20places,was%20developed%20in%20ancient%20Rome.