Two of the most common and important methods involve looking at the date of birth, and names of people or organisations.
Taking a date of birth (14th February, 1962) as an example:-

( This is the date format used in the UK - day.month.year. In the USA the common format is month.day.year. However, whichever format is used will not affect the outcome here)

Each of the 3 component parts of this date i.e. day, month, and year can be looked at separately and in various combinations to see how they interact and influence each other. Each of the components have a different significance and interpretation.
The day and the month (the l4 and 2 ) can be added together to give an overall look at the personality aspect of the person. The resulting number, in this case a 16, gives a greater understanding of the tasks involving personality growth.
Then all 3 parts can be aggregated to, give an overall number. In this case we have the 14+2 = 16 which are added in their total and not as separate digits, then added to the year number, which is added together as separate digits - e.g- 1+9+6+2 = 18. Then the two resulting numbers are added together :- 16+18 =34. The resulting number, which is 34 in this case, is seen as one of the most important numbers in the chart and can represent the aspirations of the Soul. When double numbers are used the digits are added together to give an additional and "summing up" number. In the case of the 34 then we would have a 34/7. There are many other numbers which can be derived from the date of birth, to throw further light on what is happening in the chart.

Names are easily translated into numbers by using a reduction table:

1	2	3	4	5	6	7	8	9
A	B	C	D	E	F	G	H	I
J	K	L	M	N	O	P	Q	R
S	T	U	V	W	X	Y	Z

An example of how this is applied is show below:-

	1			5				9			7	1+5+9+7=22/4
W	A	L	T	E	R		M	I	T	T	Y
5		3	2		9		4		2	2		5+3+2+9+4+2+2=27/9
												22+27=49/13/4

In this system the vowels are placed above and the consonants below and are totalled up separately, before an overall total is obtained. Y is treated as a vowel because in most cases it sounds like one phonetically.
The vowels generally signify inner qualities, and the consonants are more personality based, so the different components can be extracted and add to the understanding of the complete person, which we see in the overall total of 49/13/4.

This explanation is just a starting point and the numbers can be extended and developed using more numbers which are derived from the original date of birth and name.