Ten (10) is a positive integer one more than 9 and one less than 11.

## PropertiesEdit

10 is the base of our number system, called decimal, which is caused by the fact humans have ten fingers.

10 is a composite number, more specifically a semiprime number. It is equal to 2*5.

10 is a the fourth left factorial.

10 is the fourth triangular number (between 6 and 15). It is also the third tetrahedral number (between 4 and 20). It is the first number besides 1 with both of these properties.

The powers of ten are encountered much more often than other numbers. The next power of ten is 100. In addition, these are the basis of scientific notation.

It is one of few non-single-digit numbers that has its own emoji: 🔟

## Properties Edit

- 10 is an even composite number.
- 10 is the 4th triangular number.
- 10 is the 3rd tetrahedral number.
- A ten sided shape is called a decagon.

## In googology Edit

Due to its ubiquity as a number base, many googologisms are based on the number ten:

- All the -illion numbers and SI prefixes (deca- in particular is exactly 10)
- Googol, googolplex and their variants
- Megiston
- A large portion of Jonathan Bowers' numbers (aside from those based on 3)
- Almost all of Sbiis Saibian's numbers. Menger sponge is a counterexample.

In Greek-based number-naming systems, is associated with prefix deka-, and with prefix deca- in Latin systems.

Donald Knuth calls this number **deciad**, and it's equal to using the -yllion system.

Using Sbiis Saibian's naming system, this number is called **monologue**.^{[1]}

A number is divisible by 10 if it ends in 0. This makes ten the easiest number to test for divisibility, and is a consequence of ten as our number base.

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