Natural number
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![The Ishango bone (on exhibition at the Royal Belgian Institute of Natural Sciences)[8][9][10] is believed to have been used 20,000 years ago for natural number arithmetic.](/Images/godic/202501/30/Os_d'Ishango_IRSNB1143.JPG")
![The double-struck capital N symbol, often used to denote the set of all natural numbers (see List of mathematical symbols).](/Images/godic/202501/30/U+2115.svg1143.png")
In mathematics, the natural numbers are those used for counting (as in "there are six coins on the table") and ordering (as in "this is the third largest city in the country"). In common language, words used for counting are "cardinal numbers" and words used for ordering are "ordinal numbers".