What am I doing wrong in this problem:

The original question is:

In this problem, we explore the effect on the standard deviation of adding the same constant to each data value in a data set. Consider the following data set.

• 12,14,16,14,12

Use the defining formula, the computation formula, or a calculator to computes. (Enter your answer to four decimal places.):

I got: .8367

This is how I got it:

1. Divide for mean: 12+14+16+14+12= 68. 68/5=13.6
2. Then I added (12-13.6)^2 + (14-13.60)^2 + (16-13.6)^2 + (14-13.60)^2 + (12-13.6)^2 = 11.2
3. I found the square root of 11.2 which I found to be 3.3466.
4. I divided 3.3466 by n-1, which is 4, and got .8367.

What am I doing wrong??