In In re Marriage of Nelson, 177 Cal. App. 3d 150, 222 Cal.Rptr. 790 (Cal. Ct. App. 1986), the numerator of the fraction is "the number of months from the date of grant of each block of options to the date of the couple's separation, while the denominator is the period from the time of each grant to its date of exercisability." Id. at 793. This fraction is also multiplied by the number of shares to be purchased to determine the community figure. Id. The Nelson formula assumes that the period of employment prior to the granting of the option did not contribute to the employee earning the stock options and should not be included in the time used to calculate the community's interest in the options. See id. at 793 n.3.