year 2011 begins on saturday. in any day year 2020 will begin?
1 st Jan 2011 on Saturday
for every normal year, 1 st Jan shifted 1 day ahead but
in case of leap year it is shifted 2 days ahead.
so from 2011 to 2020 there are 2012, 2016 and 2020 are leap years
but in 2012, we are not crossing month of February.
so there are only 2 leap years
so total number of days = 9 + 2 = 11
divide 11 by 7 and find remainder
remainder = 4
so 1 jan 2020 will be on Saturday + 4 = Wednesday
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