Question by Lê Quốc Trần Anh - Discuss with MathYouLike

Lê Quốc Trần Anh Coordinator

15/03/2018 at 08:58

The 1990 and 2018 calendars are identical in the number of days in each month and the day of the week on which each day of each month occurs. In fact, the calendar repeats in these ways every 28 years until the year 2100. How many days are there in the 28 years preceding 2018?

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Doan Le Minh Hong moderators 19/03/2018 at 16:25

There are \(28 \times 365 + 7=10227\) days in those years.

Usually, a year contains 365 days, but there are some which have 366 days. Between 1990 and 2018, there are 7 years having 366 days (1992, 1996, 2000, 2004, 2008, 2012. 2016), so we have the plus 7 in the sentence.
Lê Quốc Trần Anh selected this answer.

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