To find the mean (average) of the given numbers, follow these steps:

1. Sum of the numbers: $12 + 4 + 11 + 5 + 13 + 3 + 10 + 6 = 64$

2. Count of the numbers: There are 8 numbers.

3. Mean formula: $\text{Mean} = \frac{\text{Sum of numbers}}{\text{Count of numbers}} = \frac{64}{8} = 8$

So, the mean of the given numbers is 8.

Would you like further details or explanations? Here are 5 related questions to explore the concept further:

1. How does the mean change if you add more numbers to the set?
2. What is the median of the same set of numbers?
3. How does the mean differ from the mode?
4. What happens to the mean if you multiply all the numbers by 2?
5. Can you explain how outliers affect the mean?

Tip: The mean is sensitive to extreme values (outliers), which can distort the average of a dataset.