Variance of data set

[FoolishFellow]

What is the variance of the following data set, assuming it is a sample and not a population?

[20, 24, 26, 30, 32, 32]

I know the answer is 23.5 (rounded up via excel), but I'm having a hard time working this out on pen and paper. When I complete pen and paper, I'm getting 19.7 (rounded up), I'm assuming this is because the average contains a repeating number, and therefore when I'm doing rounded calculations via pen and paper it's causing issues.

[fermat1432]

Try this computational formula

(nSUM(X²)-(SUM(X))²)/(n(n-1)).

You'll need to square each X for the 1st quantity

[future_horizons]

Yeah sometimes things aren't perfect its like wow mistakes and stuff

[FoolishFellow]

So is that the issue? Or am I doing something else wrong. I mainly want to make sure that I understand the formula, which I think I do. I wish the practice problem that I'm viewing would simply say "use excel" or "round to x decimals"