Apple Numbers '08 - Manual (Page 215)

Chapter 12 Dictionary of Functions 215
COLUMNS
The COLUMNS function counts how many columns are in a range of cells.
COLUMNS(cell-range)
 cell-range: A range of cells in a table.
Notes
If you select an entire row for cell-range, Numbers returns the total number of cells in
the row, which changes when you resize the table.
COMBIN
The COMBIN function finds the number of different ways you can combine a number of
items into groups of a specific size, ignoring the order within the groups.
COMBIN(items, size)
 items: The total number of items that can be combined.
 size: The number of items combined in each group.
Notes
Remember that combinations are not the same as permutations. The order of the items
in a group is ignored for combinations but not for permutations. For example, (1, 2, 3)
and (3, 2, 1) are the same combination but two unique permutations.
Examples
COLUMNS(B3:D10) returns 3, the number of columns in the range (columns B, C, and D).
COLUMNS(5:5) returns the total number of columns in row 5.
Examples
COMBIN(3, 2) returns 3, the number of unique groups you can create if you start with 3 items and
group them 2 at a time.
COMBIN(3.2, 2.3) returns 3. Fractional parts are dropped.
Both COMBIN(5, 2) and COMBIN(5,3) return 10.