If 28 February 2015 was Saturday, then what was the day of the week on 28 February 2021?

Sunday

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 }

28 Feb 2015;

28 + 04 + 06 + 15 + 03 = 56

remainder of \(\frac{56}{7}\) = 0

Therefore, the code of 0 is Saturday 

Similarly,

28 Feb 2021;

28 + 04 + 06 + 21 + 05 = 64

remainder of \(\frac{64}{7}\) = 01

Therefore, the code of 01 is Sunday