3. (5 points) As shown in the figure, when $n=1$, there are 2 small stars; when $n=2$, there are 6 small stars; when $n=3$, there are 12 small stars; $\cdots$; then when $n=10$, there are $\qquad$ small stars.
【Analysis】First, find the pattern for the number of small stars in the $n$th figure, and use the pattern to further solve the problem.
【Solution】Solution: When $n=1$, there are $1 \times 2=2$ small stars;
When $n=2$, there are $2 \times(2+1)=6$ small stars;
When $n=3$, there are $3 \times(3+1)=12$ small stars;
$$
\cdots \text {; }
$$

The $n$th figure has $n(n+1)$ small stars;
So when $n=10$, there are $10 \times(10+1)=110$ small stars.
Therefore, the answer is: 110.
【Comment】Based on the characteristics of the numbers and the figures, identify the pattern contained in the problem, find the pattern, and use the pattern to solve the problem.