Imagine that you've been given an estimate of 1 year and 7 and a half months (15 days) to finish a project, and you need to find the project end date. You would use the DATE function again by entering those values into cells as shown in the picture and then typing this formula into cell A6:
2011 plus the value in cell B2 is the year argument; 6 plus the value in B3 is the month argument; 9 plus the value in B4 is the day argument. Commas separate the arguments, and parentheses enclose all the arguments.
The project ends on January 24, 2013. As in the previous formula, because you typed the cell references B2, B3, and B4, instead of the values themselves, Excel can automatically update the result if those values change. If you were given more or less time to complete the project, Excel would automatically revise the result when you changed a value in cells B2, B3, or B4.