The document discusses inserting random numbers using the RANDBETWEEN formula to test a theatre booking system model. It explains that the RANDBETWEEN formula generates random numbers between the bottom and top numbers specified, in this case 0 and 4, to represent randomly booked seats. It also provides instructions to enable the Analysis ToolPak add-in if the RANDBETWEEN function does not work initially, and how to copy the formula down and across cells to populate the model with random seat bookings for testing.