Yes you can calculate your entire birth number (year and date etc.) or you can use your birth day number only. It's not a "method" it forms part of the whole process of getting closer to understanding someone/something through the use of numbers.

Single numbers represent what a person or entity (house, book, anything) appears to be in the eyes of others. They are numbers of individuality and personality.

Compound numbers reveal or indicate the karmic influences.

You can use the birthday number and the entire name of a person together to derive the appropriate numbers to do a reading. Or you can just do the full name when you don't know the birth date of a person or entity.

I prefer the Chaldean system which does not make use of number 9 in the diagram to calculate, I also feel it's far more accurate than anything else.