Ancestors are numbered on pedigree charts using a system known as the Ahnentafel numbering system. You (or the person whose ancestry is being traced) are numbered “1”. A father is twice the child’s number (1 x 2 = 2), and a mother is twice the child’s number plus one ((1 x 2 = 2 )+ 1 = 3). The individual numbered “1” can be male or female. For that person’s ancestors, all males will have even numbers and all females will have odd numbers. A paternal grandfather will be “4”. A maternal grandfather will be “6”. A paternal grandmother will be “5”. A maternal grandmother will be “7.”
On a four-generation pedigree chart, there are four columns. Person “1” is at center left. In the next column are that person’s two parents. In the third column are the four grandparents. In the fourth column the eight great-grandparents are listed. Numbers are assigned from left to right and from the top of each column to the bottom. Look again at the way the spaces are numbered on the sample pedigree chart below.
Here is an Example of the National Genealogical Standard Pedigree Chart