If on 1 January 2020 was Wednesday, then what will be the day on 28 February 2021 ?

Saturday

\(\frac{Date + Month\;code + Century\;code + Century\;upper\;year + Quotient\;of\;\frac{upper\;year}{4}}{7}\) 

\(\frac{1 + 0 + 6 + 20 + 5}{7}\) = \(\frac{32}{7}\) = Remainder 4

The day for Code 4 is Wednesday. So, it is the same day which is given

therefore,

The day for 28th february 2021 was :

\(\frac{Date + Month\;code + Century\;code + Century\;upper\;year + Quotient\;of\;\frac{upper\;year}{4}}{7}\) 

\(\frac{28 + 4 + 6 + 21 + 5}{7}\) = \(\frac{64}{7}\) = Remainder 1

The day for Code 1 is sunday