Declaration: 
TDataTable.PercentileOfNumCells (prob: double; LowCol, LowRow, HighCol, HighRow: integer; var NumData: integer): double; 
The function PercentileOfNumCells returns the percentile with the probability of prob percent. The calculation of the percentile is based on the distribution of all numeric matrix elements (cells which are neither marked as csNAN, nor as csUndefined and which belong to either interval or ratio scaled variables) between (and including) LowCol, LowRow, HighCol, and HighRow. The function returns a zero value if any error occurs. The variable parameter NumData returns the number of data points used for the calculation (i.e. the number of numeric data cells within the specified range).
Please note that the 50%percentile (prob = 50) is also known as the median of the distribution.

Hint 2: 
Setting both the low and high parameter of a dimension (i.e. LowCol and HighCol) to zero values forces the method to use all elements of that dimension. 
