How numerology works is actually quite complicated and usually requires a master numerologist to provide detailed and accurate readings. Though you can easily find your life path number and things like your expression, personality, and soul urge numbers using basic calculations, it is the way that these numbers work together that need to be interpreted properly.
The idea behind numerology is that the cosmos and your life is affected by your birth date, birth name and many other factors surrounding an individual. In this way, there are great depths that a numerology reading can go into. Consequently, it can provide often astounding insights about somebody.
It is believed that there are no coincidences in the Universe that your name and birthday affect the journey that you will take and your characteristics, in the same way, that some look at horoscopes or astrology to interpret signs or destinies.