Multidimensional means that the array can have more than three dimensions, how can I handle a four dimensions array?

Answer 1

Here is a 4 dimensional array with the name "arr".
The dimensions are 5x3x7x4
int[,,,] arr = new int[5,3,7,4]

Answer 2

But keep in mind that it's really hard to imagine an array with more than three dimensions. Use it only if it is absolutely necessary. Handling a jagged array with one-, two- or three-dimensional array is imho more clear.