There are many ways to arrive at these numbers, some are very complex!
some ways are done by adding your birth date numbers

i.e. born 12 Oct. 1944 = 1+2 + 1=0 + 1=9=4=4
=3+1+18
=4+1+8
= 1+3
= 4

The above programs will add the numbers for the names, as that can be quite complicated and take a long time

but note there are two popular methods, the Hebrew and the Pythagorean.
I'll leave it to you to experiment and see what works for you. Thought there are different ways of getting to the numbers and what they personally mean, the meaning of the numbers themselves is usually agreed upon.

A quick meaning of the numbers

1.
Everything starts with the number 1.
So people that are number One are original, start new things, they are leaders and take the initiative.

2
We start with number 1 which then becomes number 2. Hence number 2 people are aware of other people and how they react to the world around them more than number 1's.

3, Two becomes 3
so they are more social and romantic more easy going (the number is more stable), they are initiators but don't persevere as much, hence they don't tend to finish things. popular and idealistic.

4.
Fours are more stable, note most chairs and things have four legs, so are more solid and stable. Hence conservative and more sensible even old fashioned. Liking routine and order.

5.
Five's are more nonconformist, naturally curious and far more likely to take risks, they are more leaning intensive, and are generally happy so long as they can learn something from a situation.

6.
More romantic that the 3's (they are two 3's) very idealistic. They like to help and take care of other people. They tend to have an interest in music and art, and being helpful people like to teach.

7.
These are the thinkers and searchers, looking for the secret or hidden, make good researchers. They don't take things at face value but will make there own opinion and look deeper. Hence they are more philosophical and knowledgeable. But can become more isolated

8.
These people tend to be more professional, have good judgment, and sharp decisiveness in issues. They like to be in charge and feel comfortable with that position.

9.
These are charming people and are natural entertainers. Normally caring and generous. It can be hard for other people to understand them, but find it easy to make friends.

Personally I don't agree with the double numbers i.e. 11 can reduce to 2 and 22 to 4 etc. but just for reference here they are

11.
Is Intuitive (even if it becomes a 2, of before), has a more natural understanding of the psychic and spiritual.

22.
They are people that are comfortable with the spiritual but are also comfortable with the mundane (i.e. the number 4 from 2+2). They make good leaders and are naturally organized.

33.
Another spiritual number, they feel a compassion for the world and have a tendency to self sacrifice themselves.