Natural number

Natural number can mean either a positive integer ({{num|1}}, {{num|2}}, {{num|3}}, {{num|4}}, ...) or a non-negative integer ({{num|0}}, {{num|1}}, {{num|2}}, {{num|3}}, {{num|4}}, ...).

Related Topics:
Positive - Integer - Non-negative

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Natural numbers have two main purposes: they can be used for counting ("there are 3 apples on the table"), and they can be used for ordering ("this is the 3rd largest city in the country").

Related Topics:
Counting - Ordering

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Properties of the natural numbers related to divisibility, such as the distribution of prime numbers, are studied in number theory. Problems concerning counting, such as Ramsey theory, are studied in combinatorics.

Related Topics:
Divisibility - Prime number - Number theory - Ramsey theory - Combinatorics

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