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).
Ten is a composite number, its proper divisors being 1, 2 and 5. Ten is the smallest noncototient, a number that cannot be expressed as the difference between any integer and the total number of coprimes below it.
Ten is the second discrete semiprime (2.5) and the second member of the (2.q) discrete semiprime family. Ten has an aliquot sum σ(n) of 8 and is accordingly the first discrete semiprime to be in deficit. All subsequent discrete semiprimes 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.
It is the aliquot sum of only one number the discrete semiprime 14.
Ten is a semi-meandric number.
The Roman numeral for ten is X (which looks like two V's [the Roman numeral for 5] put together); it is thought that the V for five is derived from an open hand (five digits displayed). Incidentally, the Chinese word numeral for ten, is a cross, too: 十.
There are said to be Ten Lost Tribes of Israel (those other than Judah and Benjamin). There are Ten Sephirot in the Kabbalistic Tree of Life. The Bible records 10 generations between Adam and Noah, and 10 generations between Noah and Abraham.
'Ten' is an album by Y&T, Pearl Jam, Chicago, Wet Wet wet and The Stranglers.
Now we are into 2 digits enjoy ten to twenty here.