Apple Numbers '08 - Manual (Page 220)

220 Chapter 12 Dictionary of Functions
COUNTBLANK
The COUNTBLANK function counts the number of cells in a range that are empty.
COUNTBLANK(range)
 range: A single range of cells.
COUNTIF
The COUNTIF function counts the number of cells in a range that satisfy a condition.
COUNTIF(test-range, condition)
 test-range: The range of cells to be tested.
 condition: The conditional test that results in a logical TRUE or FALSE.
Notes
For more information on the comparison operators you can use in the conditional test,
see “Understanding the Comparison Operators” on page 96.
Examples
Given the following table:
COUNTBLANK(A1:E1) returns 0.
COUNTBLANK(A2:E2) returns 1.
COUNTBLANK(A3:E3) returns 2.
COUNTBLANK(A4:E4) returns 1.
COUNTBLANK(A5:E5) returns 5.
Examples
If cells A1:A8 contain 1, 2, 3, 4, 5, 6, 7, 8:
COUNTIF(A1:A8, "<4") returns 3.
COUNTIF(A1:A8, ">4") returns 4.
COUNTIF(A1:A8, ">=4") returns 5.