Number
Number is the abstract object of quanity, used to count, measure, label, ordering and code.
Numberal System
Numbers can be represented in language by symbols. For instance, both "16" and "XVI" are express the same quanity of 16. However, this only work on the relateively small number of simple symbols. Therefore, the concept of numberal system is created. It's the set of rules and combinations which allow the presentation of any number. In this system, each individual leter of the number is called a digit, can be combine with other digits, symbols and structure to express a quanity.
Number Classification
Natural Number
The set of number