Certain dates, when written down in figures, have a very
interesting appearance. On this page a list of such special
date. It is important to note that throughout the world different
formats are used to write down dates. Some common formats are:
month / day / year: English language
day - month - year: other European languages
year . month . day: Chinese language
Of course, there is also a choice from the
number of digits you chose to represent the
day, month and year. Some of these are:
DD - two digit day of the month number
(D)D - one or two digit day of the month number
MM - two digit month number
(M)M - one or two month number
YYYY - four digit year number
YY - two digit year number
(YYY)Y - one, two, three, or four digit year number
From these many different date formats can be constructed.
Double dates of this form, always appear in the first 12 years
of the century. There are a total of 257 of these day with the
first being January 1, 1001 and the last being December 31, 3112.
Some close double dates of these form are:
A palindrome is a word, number or sentense
which reads the same in reverse order.
Of course, there are also palindrome dates
(when ignoring all separation symbols).
Below a number of these dates are given,
grouped by their format.
MM/DD/YYYY and YYYY.MM.DD
There are about 31 centuries having palindrome
dates of this format. Most of these centuries
have twelve palindrome dates, one for each month.
There are a total of 331 of such palindrome dates.
Some close palindrome dates of this format are:
These kind of palindrome dates only occur in
twelve centuries, namely, those starting with 10,
11, 20, 21, 30, 40, 50, 60, 70, 80, and 90.
And in each of those ages, they every time
occur in the same month. There are a total of
335 of such palindrome dates. Note that these never
occur in October, as that would make a 01YY year,
however these dates, when written as DD-MM-YYY
are still palindrome dates.
There are a lot of these kind of palindrome dates,
especially in the first centuries. Till December 31, 9999,
there are 4090 of these kind of palindrome dates, which
makes it the most common form of palindrome date (when
the year is not abbreviated).
When using the "digital" numbers consisting of seven segments, there are also mirror dates, which read the same in the
mirror. These are rather rare, because they can only make use of the digits 0,
2, 5, and 8. (One could also include the digit 1, which in the mirror reads
like 1 as well, but then in the wrong place.)
MM/DD/YYYY and YYYY.MM.DD
All mirror dates of this form lay in the future. They are:
When using the "digital" numbers consisting of seven segments, there are also
rotation dates, which read the same when rotated over 180°. These are rare,
because they can only make use of the digits 0, 2, 5, 6, 8, and 9.
(One could also include the digit 1, which in the mirror reads like 1 as
well, but then in the wrong place.)