An eyewitness to a crime said that the license plate of the getaway car began with the letters T, N, E, and Q, but he could not remember the order. The rest of the plate had the
numbers 4, 9, 8, and 7, but again he did not recall the order. How many license plates must the police investigate to find the car?
There are license plates for the police investigate.
(Type a whole number.)