GMEAN returns the geometric mean of the specified cell range
GMEAN(Cell Range):
Cell Range: The cell range to anaylze. i.e. (A1:A31)
NOTES:
The GMEAN function only works with numeric cells and ignores zeros (0). If you need to handle data qualifiers or handle zeros differently use GGM, GGMZ or STATZ.
EXAMPLES:
GMEAN(C4:C22)