I honestly have never heard of it before you made this thread...but I looked it up and found this: https://mysteries24.com/n-48694-Divination_by_the_Pythagorean_System#:~:text=Divination%20by%20the%20Pythagorean%20system%20is%20the%20summation,example%2C%20let%27s%20say%20your%20birth%20date%20is%2001%2F09%2F1974.
It seems to tie into numerology, although I don't know how accurate this may be. Maybe HP Cobra knows more, He also made a page about numerology in recent months.