Because the field is in text format , we run the risk of introducing even more errors - the user could type in letters, symbols, or impossible dates, because Excel will not restrict the information that should be entered there. If no selection was highlighted when you opened the Format Cells window, it means that the selected cells have different formats. Some may be text, some may be dates, etc. For Y2K compliance, the information in column C should first be given the correct century extension and then converted to a date format. If the dates are all recent, you could try converting the selected cells to date format that uses a 4-digit century, and allow Excel to mask the correct century.
Applications use different methods to determine the century, and they can guess wrong.
Commonly, dates that are either close the millenium or thirty- to forty years in the past have the largest range for error. In the example below we see a few rows of information in a Microsoft Access format. In reality, the full date, with 4-digit century, is held in the data file, and the file is Y2K compiant. Unfortunately, this ability to remember a full date but display a condensced date can confuse the user. K compliant dates is to set the application to accept only those dates, and then make sure that every external source, whether data files or manual entry, is also providing the correct 8-digit date.