To find out how many teenagers attended the game, we need to calculate 10% of the total number of attendees, which is 3200.
We can calculate this as follows:
\[ \text{Number of teenagers} = 10% \times 3200 \]
First, convert 10% to a decimal:
\[ 10% = \frac{10}{100} = 0.10 \]
Now, multiply 0.10 by 3200:
\[ \text{Number of teenagers} = 0.10 \times 3200 = 320 \]
Therefore, the number of teenagers who attended the game is \( \boxed{320} \).