If 19 September 1999 was Sunday, then what was the day of the week on 19 January 2001?

Friday

Using Code Method :-

\(\frac{Date+Month code+Year code+Last 2 digits of yr+Leap yrs till given yr}{7}\)

( Note: Remainder of the above sum will be the code of week day }

19 Sep 1999;

19 + 06 + 0 + 99 + 24 = 148

remainder of \(\frac{148}{7}\) = 01

Therefore, the code of 01 is Sunday

Similarly,

19 Jan 2001;

19 + 01 + 06 + 01 + 0 = 27

remainder of \(\frac{27}{7}\) = 06

Therefore, the code of 06 is Friday