For example to find the serial number for the date taking the values in cells A2 A3 and A4 as the year month and day arguments respectively the formula is. Type the initial date in the first cell. SUMIFSB2B10 C2C10 9102020 C2C10.
In this system 2-Jan-1900 is stored as the number 2 3-Jan-1900 as 3 and so on.
Then type a formula like one of the following. When the month is less than or equal to zero Excel will subtract the absolute value of month plus 1 from the first month of the specified year. First put a start date in a cell and an end date in another. Supply values or cell references for the formula arguments.