The formula for variance is:
\[
\text{Variance} = \frac{\sum (x_i - \bar{x})^2}{n}
\]
where \( \bar{x} \) is the mean of the numbers and \( x_i \) are the individual numbers.
First, calculate the mean of the numbers:
\[
\bar{x} = \frac{2 + 4 + 5 + 6 + 8 + 17}{6} = 7
\]
Then, calculate the squared differences from the mean for each number, sum them up, and divide by \( n \).
\[
\text{Variance} = \frac{(2-7)^2 + (4-7)^2 + (5-7)^2 + (6-7)^2 + (8-7)^2 + (17-7)^2}{6} = 22
\]