Thank you for the opportunity to help you with your question!
The problem is when you square the difference between the value of x and mean you are getting negative answers. These answers will always be positive. For example, for your value 0.56; you do 0.56 - 0.719 = -0.159; Then (-0.159)^2 = 0.025281; not -0.025281. A negative times a negative is positive.
My guess is you are doing this on your calculator. When we square a negative number, we must put the negative number inside parentheses.
So, each of your negative values should be positive. If I added correctly, that would give you 0.802687 on top.
0.802687/6 = 0.1338
Please let me know if you have any quesitons.
Please let me know if you need any clarification. I'm always happy to answer your questions.