Apple Numbers '08 - Manual (Page 256)

256 Chapter 12 Dictionary of Functions
PERCENTILE
The PERCENTILE function finds the value within a range of values that corresponds to a
particular percentile.
PERCENTILE(data, percentile)
 data: A range of cells containing the data.
 percentile: The percentile value you want to find.
PI
The PI function returns the approximate value of pi, the ratio of a circle’s circumference
to its diameter, accurate to 15 decimal places.
PI()
 No arguments (but you must include the parentheses).
Examples
Given the following table:
PERCENTILE(A2:E2, 0.5) returns 80, the 50th percentile of the range.
PERCENTILE(A4:E4, 0.5) returns 90, the 50th percentile of the range.
Examples
PI() returns 3.14159265358979.
SIN(PI()/2) returns 1, the sine of PI/2 radians or 90 degrees.