Ahnentafel numbers provide a simple means of representing the direct ancestors of an individual by numbers. If the base individual is given the number 1, then this person's father is numbered 2, and the mother 3. This pattern is then repeated, so that for each individual, with number n, the father is numbered 2n, and the mother 2n+1. Thus the base individual's paternal grandfather is numbered 4, and paternal grandmother 5; and the maternal grandparents are numbered 6 and 7.