Syntax: @ISNUMBER(X)
X = a numeric value
@ISNUMBER returns 1 if X is a numeric value, otherwise 0. Blank cells are considered numeric.
Examples:
@ISNUMBER(C10) = 0, where C10 = ``Total''
@ISNUMBER(D10) = 1, where D10 = $1000.00
@ISNUMBER(A1) = 1, where A1 is blank