Type 13/8/2002 into a cell in Microsoft Excel, press enter, then right click with your mouse, choose Format Cells and change Date format to the one showing the day of the week. The answer is Tuesday.
August 13, 1959, was a Thursday.
August 13 1999 was a Friday.
August 13, 1960 fell on a Saturday.
August 13, 1990 was a Monday.
Tuesday
Thursday
August 13, 1976 was most certainly a Friday. (Boo!)
13th, August, 1966, was a Saturday.
August 13, 1963 fell on a Tuesday.
Saturday
It was a Friday.
This varies from year to year. The 13th, August, 2010, is a Friday.