My former gf was very into a specific type of numerology, where one's personal number was calculated by the number of days in the year before and after one's birthday. For example someone born on January 1st would be a 1-4 (1 for 1 day before/as of your birthday, 4 for 364 days after=3+6+4=13=1+3=4), February 2nd would be a 6-8 (Feb 2=33 days=3+3=6, 332 days after =3+3+2=8), etc. Everyone is a 1-4, 2-3, 3-2, 4-1, 5-9, 6-8, 7-7, 8-6, or 9-5. According to her being a 7-7 is best, somehow. Leap years are dealt with by figuring the 1st number only. Other than dealing with leap years it doesn't matter to this numerology what year one was born in.
She never specified what subset of numerology it was, just "numerology" as if it was the only numerology there was. She's dead now so I can't ask her even if I wanted to and if she'd answer in any kind of specifics, which knowing her she probably wouldn't.