This isn't really a math question but the answer is Sunday
7 May 1971 was a Friday.
7 July 1971 was a Wednesday.
Thursday October 7, 1971
December 7, 1971 fell on a Tuesday.
January 7, 1971 fell on a Thursday.
Monday
It was a Sunday.
7 November 1946 was a Thursday.
7 November 1861 was a Thursday.
November 7 1968 was a Thursday.
November 7 1981 was a Saturday.
November 7 2009 was a Saturday.