800 Tables for 6 Sites In a WP Multisite Installation

I am wondering if I have tables that need to be cleared from my database. I see a lot of wp_3_... and then I find a set with wp_3_2_....and so forth. Are these duplicates. Many show they are empty. I am using about 5 to 10 plugins that are popular. So, I am hoping that they are maintaining themselves properly. However, I am not a power user and I am suprised at the number of tables in my database. Does the number format tell me what I have?