Excel 2007 : Count the number of consecutive days worked and highlight

Count the number of consecutive days worked
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Hi,

I have an excel spreadsheet to record employee consecutive workdays.

It is set on as a grid e.g. column A stores all the dates and column B stores all the employee names from a drop down.

At this time I need to highlight in yellow, an employee has worked 16 consecutive days, and in red when an employee has worked 19 days. At the very least I need the 19 consecutive days worked in red.

If this is possible I would greatly appreciate help, all my contacts are stumped!

Any and all help would be much appreciated!

Thanks