I ahve a spreadsheet with several thousand rows of information. Column A of
the spreadsheet contains a date reference as follows:

A
1 1/12/93
2 1/17/93
3 2/5/94
4 12/12/03

I want to use a pivot table to report this information by month and by year.
I would like to change the date reference in each of the rows in Column A so
that the day of the month reference would be 1. The above cells would now
look as follows:

A
1 1/1/93
2 1/1/93
3 2/1/94
4 12/1/03


How can I easily accomplish this?