There are many different numbering schemes for assigning numbers to entities. These generally require an agreed set of rules, or a central coordinator.
Numbering schemes include:
The E.164 numbering plan for telephone numbers, including:
... 100 females there are 102.1 males. For every 100 females age 18 and over, there are 100.8 males.
The median income for a household in the town is $57,038, and the median ...