How many days are there in 400 years of the current western (Gregorian) calendar?

There are 365 days in every year plus an extra one in leap years. Leap years are years which number is divisible by 4 except century years. They in turn have to be divisible by 400. The years 1900, 2100, 2200 and 2300 are not leap years, but 2000 and 2400 are.

This is because the Earth travels around the sun once every 365.2425 days. February 29th is included in leap years to compensate for the accumulated difference. (365 and a quarter days was generally used during the 20th century because it wasn't envisaged to affect anyone then alive. It was a close enough approximation to have a-leap-year-every-four-years.)

More Info: en.wikipedia.org

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14 Comments

Lynne Zeman

Yep. I figured 400 x 365 plus 100 for leap days, but did not consider leap years are not applicable in century years. Blast!

wexlerbob

You did not specify which 400 years. I am sure there could be other answers for other time frames. Perhaps 1100 to 1500.

Ray Anderson

wexlerbob, 1100 to 1500 is 401 years.

Peter Gilchrist

On the turn of the century the leap year is omitted, but on the turn of the millennium it is kept, this takes care of the minor variations of day length. So the 146097 answer is not correct

Special Patrol Group

The answer given is not in your explanation therefore not confirming the answer.

Rafi Manory

The answer cannot refer to specific years bwcause the question was not phtased that way. However,, in any 400 years there would be the same number of leap years. The calculation itself should be shown (and the quarter day cannot be taken into account).