perplexus.info :: General : Coincidental Days

Coincidental Days (Posted on 2012-02-16)

A "coincidental day" corresponds to a date when both the date and its reversal, expressed in the mm-dd-yyyy format, shares the same day of the week.

For example, 09-22-2020 (in mm-dd-yyyy format) will occur on a Tuesday. Reversing the digits and expressing it in mm-dd-yyyy format, we obtain 02-02-2290 which will occur on a Sunday. Therefore, September 22, 2020 is NOT a coincidental day.

(i) Determine the total number of coincidental days between January 1, 2001 and December 31, 2099.

(ii) Determine the number of coincidental days that fall on a Sunday in the period covered under (i).

(iii) What is the last coincidental day in the period covered under (i)?

Submitted by K Sengupta

No Rating

Solution: (Hide)

(i) There are 631 occurrences of coincidental days between January 1, 2001 and December 31, 2099.

(ii) Number of coincidental days that fall on a Sunday in the period covered under (i) is 92.

(iii) The last coincidental day in the period covered under (i) is 12-30-2090, a Saturday (as was 09-02-0321 in the Julian Calendar.)

For a detailed explanation, refer to the solution submitted by Charlie in this location.

Comments: ( You must be logged in to post comments.)

Subject	Author	Date
With requirement of a 21st century reversal....	Dej Mar	2012-02-19 15:06:03
computer solution	Charlie	2012-02-16 15:34:41

Please log in:

Login:
Password:
Remember me:

Sign up! \| Forgot password

Search:

Search body:

Forums (0)
Newest Problems
Random Problem
FAQ | About This Site
Site Statistics
New Comments (3)
Unsolved Problems
Top Rated Problems
This month's top
Most Commented On

Chatterbox:


perplexus dot info