Answers

2015-09-16T14:50:54+05:30
Because the leap year is happened after every 4 years.the 28 day is come in every common years and 29 days comes after the leap year.

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2015-09-16T14:51:37+05:30
Evry fourth yr we add an extra day to the month Feb as we have the least number of days in that particular month the earth takes 365 1/4 days to complete one revolution around its orbit hence we consider 365 days as a year and the 1/4 day is added after 4 year to make a day that is 1/4+1/4+1/4+1/4=4/4=1/1=1 and why it is added in the month of Feb there is a story behind it I don't knw about that in brief BT surely u can search on google
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