lateral thinking - What is the number of the parking spot?

One needs to find the number under the car.

Answer

I believe the most obvious answer is:

There is a usual sequence of numbers, we're just looking at it in the wrong direction. The numbers of the parking spots must be viewed from the outside in, as a driver would see them, which is upside-down from the current view.

The shown numbers are: 86, ??, 88, 89, 90, 91. Therefore the answer is 87.