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:
... 6.7% from 18 to 24, 33.6% from 25 to 44, 20.6% from 45 to 64, and 9.6% who are 65 years of age or older. The median age is 35 years. For every 100 females there are 96.9 ...