This issue is corrected in 1.0v3.
ClarisWorks cannot compute the Standard Deviation or Variance for a certain number of cells (population size). For example, a cell with the formula =Var(A1..A500) may return a negative number while the definition of variance prohibits negative numbers. Since Standard Deviation is defined as the square root of Variance and it's impossible to have a square root of a negative number, ClarisWorks will return #NUM! for a cell with the formula =StDev(A1..A500).
In this example, you can get around the issue by putting =A1^2 into cell B1, then selecting B1 to B500 and choosing Fill Down from the Calculate menu. This creates a range of numbers that are the square of your current data which can be used with the following formulas to derive the Variance or Standard Deviation.
Instead of Var(A1..A500) use:
=(1/(COUNT(A1..A500)-1))*(SUM(B1..B500)-((SUM(A1..A500)^2)/COUNT(A1..A500)))
Instead of StDev(A1..A500) use:
=SQRT((1/(COUNT(A1..A500)-1))*(SUM(B1..B500)-((SUM(A1..A500)^2)/COUNT(A1..A500))))