To find the mean of the data, follow these steps:

1. List of numbers: $2, 3, 1, 9, 10, 5, 7, 8, 6$
2. Sum of the numbers: $2 + 3 + 1 + 9 + 10 + 5 + 7 + 8 + 6 = 51$
3. Count of numbers: $9$
4. Mean: $\frac{51}{9} = 5.67$

The mean of the data is $5.7$ (rounded to 1 decimal place).

Would you like more details or have any questions?

Here are five related questions:

1. How do you calculate the median of this data set?
2. What is the mode of the data set?
3. Can the mean be affected by outliers, and if so, how?
4. What is the difference between the mean and the median?
5. How would the mean change if you added another data point, say 12?

Tip: The mean provides an average but doesn’t account for the spread of the data, so it's useful to also consider measures like variance or standard deviation.