Can I perform math operations on date and time data columns?
Dates are stored internally as the total number of seconds since Jan. 1, 1904. Times are stored as a total number of seconds from time 0.
It is possible to display how the value is stored internally by simply setting an empty column (formatted as Double) equal to the column containing dates or times. If c0 contains dates when the formula c1=c0 is executed, c1 will contain the number of seconds between Jan. 1, 1904 and the date.