# What is the standard deviation of just one number?

##### 1 Answer

Nov 16, 2015

zero

#### Explanation:

If you have just one number or a *million* numbers that are exactly the same (such as all are 25), the standard deviation will be **zero** .

In order to have a standard deviation **greater than zero** , you must have a sample that contains values that are **not the same** .

So, at a minimum, you need at sample with **at least two values** that are not equivalent in order to have a standard deviation greater than zero.

hope that helps