Editing Ahnentafel (section)

==Inductive reckoning==
To find out what someone's number would be without compiling a list, one must first trace how they relate back to the subject or person of interest, meaning that one determines for example that some ancestor is the subject's father's mother's mother's father's father. Once one has done that, one can use two methods.

===First method===

Use the definition that a father's number will be twice that individual's number, or a mother's will be twice plus one, and just multiply and add 1 accordingly. For instance, someone can find out what number [[Sophia of Hanover]] would be on an ahnentafel of [[Peter Phillips]] (son of [[Anne, Princess Royal|Princess Anne]] and grandson of [[Elizabeth II]]). Sophia is Phillips's mother's mother's [[George VI|father]]'s [[George V|father]]'s [[Edward VII|father]]'s [[Queen Victoria|mother]]'s [[Prince Edward, Duke of Kent and Strathearn|father]]'s [[George III of the United Kingdom|father]]'s [[Frederick, Prince of Wales|father]]'s [[George II of Great Britain|father]]'s [[George I of Great Britain|father]]'s [[Sophia of Hanover|mother]]. So, we multiply and add:

:1×2&nbsp;+&nbsp;1&nbsp;=&nbsp;3
::3×2&nbsp;+&nbsp;1&nbsp;=&nbsp;7
:::7×2&nbsp;=&nbsp;14
::::14×2&nbsp;=&nbsp;28
:::::28×2&nbsp;=&nbsp;56
::::::56×2&nbsp;+&nbsp;1&nbsp;=&nbsp;113
:::::::113×2&nbsp;=&nbsp;226
::::::::226×2&nbsp;=&nbsp;452
:::::::::452×2&nbsp;=&nbsp;904
::::::::::904×2&nbsp;=&nbsp;1808
:::::::::::1808×2&nbsp;=&nbsp;3616
::::::::::::3616×2&nbsp;+&nbsp;1&nbsp;=&nbsp;'''7233'''

Thus, if we were to make an ahnentafel for Peter Phillips, Electress Sophia would be #7233, among other numbers due to [[royal intermarriage]] causing [[pedigree collapse]]. (See [[#Multiple numbers for the same person]] below.)

===Second method===
Write down the digit "1", which represents the subject, then from left to right write "0" for each father and "1" for each mother in the relation, ending with the ancestor of interest. The result will be the [[Binary numeral system|binary]] representation of the ancestor's ahnentafel number. Then convert the binary number to decimal form. Using the Sophia example:

:Sophia = Peter's mother's mother's father's father's father's mother's father's father's father's father's father's mother
:Sophia = 1110001000001
:1110001000001 = ['''1'''×4096] + ['''1'''×2048] + ['''1'''×1024] + ['''0'''×512] + ['''0'''×256] + ['''0'''×128] + ['''1'''×64] + ['''0'''×32] + ['''0'''×16] + ['''0'''×8] + ['''0'''×4] + ['''0'''×2] + ['''1'''×1]
:Sophia = 7233