[Guest]

May 5th is a palindromic date, because it can be written 5/5. Ignoring the slash, 55 is a palindromic number, written the same forwards and backwards.

Ignoring year, how many palindromic dates are there? List them all.

(Careful, no leading zeroes to any months or days!)

Careful! This is a harder riddle than it initially appears!

[Guest]

1/1

1/11

1/21

1/31

2/2

2/12

2/22

3/3

3/13

3/23

ahh, sorry, gotta run

[HoustonHokie]

May 5th is a palindromic date, because it can be written 5/5. Ignoring the slash, 55 is a palindromic number, written the same forwards and backwards.

Ignoring year, how many palindromic dates are there? List them all.

At first, I was trying to figure out if the "/" was part of the palindrome, or if it was ignored. Rather than ask questions, I answered it both ways.

If "/" is part of the palindrome, I get:

11 dates:

1/1

2/2

3/3

4/4

5/5

6/6

7/7 (my b-day!)

8/8

9/9

11/11

12/21

If it's just the number, I get:

32 dates:

1/1

1/11

1/21

2/2

2/12

2/22

3/3

3/13

3/23

4/4

4/14

4/24

5/5

5/15

5/25

6/6

6/16

6/26

7/7 (still my b-day!)

7/17

7/27

8/8

8/18

8/28

9/9

9/19

9/29

10/1

11/11

12/1

12/21

[Guest]

At first, I was trying to figure out if the "/" was part of the palindrome, or if it was ignored. Rather than ask questions, I answered it both ways.

If "/" is part of the palindrome, I get:

11 dates:

1/1

2/2

3/3

4/4

5/5

6/6

7/7 (my b-day!)

8/8

9/9

11/11

12/21

If it's just the number, I get:

32 dates:

1/1

1/11

1/21

2/2

2/12

2/22

3/3

3/13

3/23

4/4

4/14

4/24

5/5

5/15

5/25

6/6

6/16

6/26

7/7 (still my b-day!)

7/17

7/27

8/8

8/18

8/28

9/9

9/19

9/29

10/1

11/11

12/1

12/21

forgot 11/1

[Guest]

forgot 11/1

You came up with 33 dates.

33 dates is the best answer with thinking inside the box.

However, I've come up wth at least 17 other answers, for a total of 50.

Remember, the slash does NOT matter, otherwise, I could have come up with a WHOLE lot more.

No more hints for now! Where am I (perfectly legitimately) getting 17 more answers from?

[Guest]

Isn't 34 dates the "inside the box" answer, given that 1/31 is not on that list?

You came up with 33 dates.

33 dates is the best answer with thinking inside the box.

However, I've come up wth at least 17 other answers, for a total of 50.

Remember, the slash does NOT matter, otherwise, I could have come up with a WHOLE lot more.

No more hints for now! Where am I (perfectly legitimately) getting 17 more answers from?

[Guest]

You have roman numerals in mind? Then 1/6, 4/1, 9/1, 5/4, 6/5, 6/4, 8/5, 7/4, 8/4, 10/9, 11/10, 11/9, 12/10, 12/9, 10/20, 9/21

You came up with 33 dates.

33 dates is the best answer with thinking inside the box.

However, I've come up wth at least 17 other answers, for a total of 50.

Remember, the slash does NOT matter, otherwise, I could have come up with a WHOLE lot more.

No more hints for now! Where am I (perfectly legitimately) getting 17 more answers from?

[Guest]

However, I've come up wth at least 17 other answers, for a total of 50.

Remember, the slash does NOT matter, otherwise, I could have come up with a WHOLE lot more.

No more hints for now! Where am I (perfectly legitimately) getting 17 more answers from?

10/1

11/1

12/1

13/1

14/1

15/1

16/1

17/1

18/1

19/1

20/2

21/2

22/2

23/2

24/2

25/2

26/2

27/2

28/2

29/2

30/3

31/3

we can add 22 more (edit: only in a leap year, lest we'd have to remove the extra day)

Edited May 5, 2008 by ChuckJerry

[Guest]

33

[Guest]

we can add 22 more (edit: only in a leap year, lest we'd have to remove the extra day)

10/1

11/1

12/1

13/1

14/1

15/1

16/1

17/1

18/1

19/1

20/2

21/2

22/2

23/2

24/2

25/2

26/2

27/2

28/2

29/2

30/3

31/3

Except the 11th of January and the 22nd of February are already counted. I like your answer, though. I didn't think of that.

[Guest]

You came up with 33 dates.

33 dates is the best answer with thinking inside the box.

However, I've come up wth at least 17 other answers, for a total of 50.

Remember, the slash does NOT matter, otherwise, I could have come up with a WHOLE lot more.

No more hints for now! Where am I (perfectly legitimately) getting 17 more answers from?

I have 51 answers... unless I've duplicated one somewhere:

Month-Day

1/1

1/11

1/21

1/31

2/2

2/12

2/22

3/3

3/13

3/23

4/4

4/14

4/24

5/5

5/15

5/25

6/6

6/16

6/26

7/7

7/17

7/27

8/8

8/18

8/28

9/9

9/19

9/29

10/1

11/1

11/11

12/1

12/21

Day-Month

10/1

12/1

13/1

14/1

15/1

16/1

17/1

18/1

19/1

20/2

21/2

23/2

24/2

25/2

26/2

27/2

28/2

31/3

Borrowing slightly from other posts.

[Guest]

There are only 33 palindromic dates in a year if you use the Month-Day format without using any leading zeros.

The only way you can get more is by using tricks such as using Day-Month, roman numerals etc... which is essentially repeating the same date in a different way, so it shouldn't count...

Please correct me if I am wrong....

[itachi-san]

You have roman numerals in mind? Then 1/6, 4/1, 9/1, 5/4, 6/5, 6/4, 8/5, 7/4, 8/4, 10/9, 11/10, 11/9, 12/10, 12/9, 10/20, 9/21

If you're going to use roman numerals there are WAY more, and I also don't think this is intended because it makes for more than 50 total.

1/2, 1/3, 2/1, 2/3, etc... adds up to a lot more than 50 total.

[Guest]

Thinking European was my solution for the extra ones. I like the Roman numeral idea though. Nice job ChuckJerry and everyone else!