How is standard deviation of laboratory results calculated?

you find the mean or average of all the numbers, then you subtract all of your data values or trials from the mean, for example if your mean was 3 and you had five data values it would look something like this. 4-3=1 5-3=2 2-3=-1 3-3=0 5-3=2. you then square all of those results and add them so you end up with 1+4+1+0+4=10 ten is your variance, find the square root of the variance so square root of 10 is