I have a spreadsheet in which I need to be able to track a patient at certain

intervals from date of enrollement. For example, If I have and enrollment

date of 10/11/07, I need to know the exact date for 30 days later, 90 days

later, 6 months later, 12 months later.

How can I do this?

Excel stores dates as the number of days from 1/1/1900. That means that

date calculations are simply done as addition and subtraction. All you

have to do is add the number of days since the initial day and you'll

have it. In order for it to be displayed as a date you'll need to

format the cell as Date.

For example, using your example, 10/11/07 is stored in Excel as 39366.

But if the cell is formatted as Date it will display as 10/11/2007 or

whatever date format you've chosen. In the 30 day cell you'd simply

have a formula +A1+30 (assuming the original date is stored in cell A1)

and the new cell will read 11/10/2007 which is 30 days later.

The nice thing is that Excel understands that you likely want the new

cell formatted as Date since the original cell was formatted as such.

I hope that helps!