Q. If it was Saturday on 17th December, 1982 what will be day on 22nd December 1984?

Explanation by: Vishal Gupta

Clearly, every day repeats itself on the seventh day. Now, 17th December 1982 to 17th December 1983 is a period of 365 days. Dividing by 7, we get 52 weeks and one day. Thus, the 365th day will be the same as the first day i.e., 16th December 1983 is also Saturday.
Now, 16th December 1983 to 16th December 1984 is a period of 366 days (because 1984, being a leap year, has 29 days in February). Thus, as shown above, 14th December 1984 is also Saturday and thus, 22nd December 1984 is a Sunday.