Published on Nov 8, 2019

# 10 Number Background Images

License Info: Creative Commons 4.0 BY-NC

10 (ten) is an even natural number following 9 and preceding 11. Ten is the base of the decimal numeral system, by far the most common system of denoting numbers in both spoken and written language. The reason for the choice of ten is assumed to be that humans have ten fingers (digits).

## In Mathematics

Ten is a composite number, its proper divisors being 1, 2 and 5. Ten is the smallest noncototient, a number that can not be expressed as the difference between any integer and the total number of coprimes below it.

Ten is the second discrete biprime (2.5) and the second member of the (2.q) discrete biprime family. Ten has an aliquot sum σ(n) of 8 and is accordingly the first discrete biprime to be in deficit. All subsequent discrete biprimes are in deficit. The aliquot sequence for 10 comprises five members (10,8,7,1,0) with this number being the second composite member of the 7-aliquot tree

Ten is a semi-meandric number.

Ten is the sum of the first three prime numbers and also of the first four factorials. Ten is the eighth Perrin number, preceded in the sequence by 5, 5, 7.

Ten squared equals 100.