Vedic Numerology is an ancient system which uses Planets and numbers associated with planetary beings, to make predictions. Each number has their own planet and lord associated with them.
There are simple calculations based on Planets, alongside other calculations of Dashas, Antardashas, Prati Antardasha, and some of the yogs to give accurate predictions.
One's date of birth is also factored in, where basic numbers and destiny numbers are calculated, after which the predictions start.
This is a simple system through which accurate guidance is provided.