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Palindrome Day

Palindrome Week: May 10 - May 19, 2015 are all Palindrome Days (m/dd/yy).

A Palindrome Day happens when the day’s date can be read the same way backwards and forwards. The dates are similar to word palindromes in that they are symmetrical.

Palindromes read the same way forwards and backwards, like 'BOB'.
'BOB' is feeling lucky on his Palindrome Day. Palindrome dates read the same way backwards and forwards.

Because date formats vary from country to country, not all dates that are be considered palindromic in one kind of date format are Palindrome Days in another. For instance, June 10, 2016 or 6-10-2016 is a palindromic date in the month-day-year (m-dd-yyyy) format, but is not if you write the date as mm-dd-yyyy (06-10-2016); as day-month-year (dd-mm-yyyy: 10-06-2016) or as year-month-day (yyyy-mm-dd: 2016-06-10).

Different Digits

In addition to the format, many people around the world also write the digits on the date differently. For instance, it is common to write only the last two digits of the year – so, 15 instead of 2015. Other such representations include:

  • d-m-yyyy or 10-5-2015
  • d-m-yy or 10-5-15
  • dd-md-yy or 10-05-15
  • mm-dd-yy or 05-10-15

Each of these date formats has its own Palindrome Days.

Illustration image
Whether a date is palindromic or not depends on how it is written.
Whether a date is palindromic or not depends on how it is written.

Some Palindrome Dates are Rare

Depending on date formats, palindromic dates can be rare. Aziz S. Inan, an electrical engineering professor at the University of Portland, Portland, U.S.A. has calculated that in the mm-dd-yyyy format, Palindrome Days tend to occur only in the first few centuries of each millennium (1000 years). The last palindromic date in the second millennium (years 1001 to 2000) in this format was August 31, 1380 or 08-31-1380.

According to Dr. Inan, in the mm-dd-yyyy format, the first Palindrome Day in the current millennium (January 1, 2001 to December 31, 3000) was October 2, 2001 (10-02-2001). The last Palindrome Day in the millennium will be September 22, 2290 (09-22-2290).

There will be 12 Palindrome Days in the 21st century if you write your date in the mm-dd-yyyy format. The first one was on October 2, 2001 (10-02-2001) and the last one will be on September 2, 2090 (09-02-2090).

In the dd-mm-yyyy format, there are 29 Palindrome Days in the current century. The first was 10 February, 2001 (10-02-2001). The last is a special one – it's a leap day! 29 February, 2092 (29-02-2092) will be the last Palindrome Day of the 21st century.

Over a Week of Palindromes

In 2015, people who write their dates in the m-dd-yy format will be treated to 10 consecutive days of palindromic dates. Every day from May 10, 2015 (5-10-15) to May 19, 2015 (5-19-15) will have a palindromic date.

Such an extended period of back-to-back Palindrome Days in the m-dd-yy format are not that rare. Every year since 2011 have had 10 consecutive Palindrome Days. In 2011, they occurred from January 10, 2011 (1-10-11) to January 19, 2011 (1-19-11). In 2012, the same sequence of dates occurred in February and 2013 it happened in March. In 2016, this will happen in the month of June.

Notice a pattern here? As long as you write your date in the m-dd-yy format, every century has 9 years with 10 Palindrome Days in a row. These years are always in the second decade of the century. For example, every year between 2011-2019, 2111-2119, and 2211-2219 will have 10 consecutive Palindrome Days. This is true for previous centuries as well.

The month this happens corresponds to the last digit of the year. For instance in 1918, 2018 and 2118, the 8th month of the year, August, will have 10 Palindrome Days. Each of these days will begin on the 11th day of the month and end on the 19th.

More Upcoming Palindrome Days

m-dd-yyyy format
  • June 10, 2016 (6-10-2016)
d-mm-yyyy format
  • 5 October 2015 (5-10-2015)
  • 6 October 2016 (6-10-2016)

Topics: Dates, Calendar

In this Article


Special Date Combinations

  1. Palindrome Day
  2. The 823 Years Myth
  3. 12/12/12
  4. 11/11/11
  5. 10/10/10
  6. Date Pattern Calculator

Special Calendar Dates

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