This is another trick question since Pope Gregory did not create the Gregorian calendar until 1582, and then it only went into effect gradually around the work over the next 400 years or so. However, if someone poses this question to you, as they inevitable will with one pre-Gregorian calendar date or another, humor them and say "To translate this properly, one would have to make a complex technical conversion from the Gregorian calendar to the Julian (or whatever) calendar, however, let's assume that none is necessary and let's compute the DoW by the conventional formula." The say out loud, "5 plus 25 plus 1 plus 0 minus 0 equals 31, and 31 minus minus 28 equals 3, which equals Tuesday."
