Whats up with how the slides are numbered?
The slide numbers (and letters) that are in the corner of each slide thumbnail in the Presentation Panel are mapped to your keyboard. For instance, the first row of keys, 1234567890, are mapped to the first rows of slides that are visible in your presentation. The next row of keys, QWERTYUIOP, are mapped to the following slides. While the “Slide 2 tab” is selected, pressing one of the keyboard keys will trigger the slides that they are mapped to on your screen.