# Binary Dates in 2010 and 2011

People have been tweeting about the upcoming dates that look like binary numbers. 10/10/10 seems to be a favorite, both because of its symmetry and because 101010 = 42 in decimal (you know, the answer to the ultimate question of life, the universe, and everything). Here are the nine dates in 2010, interpreted as binary numbers, and with their decimal equivalents:

Binary Dates in 2010 (mm/dd/yy)
Date mm/dd/yy Binary Decimal
January 1st, 2010 1/1/10 1110 14
1/01/10 10110 22
January 10th, 2010 1/10/10 11010 26
January 11th, 2010 1/11/10 11110 30
October 1st, 2010 10/1/10 10110 22
10/01/10 100110 38
October 10th, 2010 10/10/10 101010 42
October 11th, 2010 10/11/10 101110 46
November 1st, 2010 11/1/10 11110 30
11/01/10 110110 54
November 10th, 2010 11/10/10 111010 58
November 11th, 2010 11/11/10 111110 62

Here they are in dd/mm/yy format:

Binary Dates in 2010 (dd/mm/yy)
Date dd/mm/yy Binary Decimal
January 1st, 2010 1/1/10 1110 14
1/01/10 10110 22
January 10th, 2010 10/1/10 10110 22
10/01/10 100110 38
January 11th, 2010 11/1/10 11110 30
11/01/10 110110 54
October 1st, 2010 1/10/10 11010 26
October 10th, 2010 10/10/10 101010 42
October 11th, 2010 11/10/10 111010 58
November 1st, 2010 1/11/10 11110 30
November 10th, 2010 10/11/10 101110 46
November 11th, 2010 11/11/10 111110 62

## 2011

The same days also look like binary in 2011:

Binary Dates in 2011 (mm/dd/yy)
Date mm/dd/yy Binary Decimal
January 1st, 2011 1/1/11 1111 15
1/01/11 10111 23
January 10th, 2011 1/10/11 11011 27
January 11th, 2011 1/11/11 11111 31
October 1st, 2011 10/1/11 10111 23
10/01/11 100111 39
October 10th, 2011 10/10/11 101011 43
October 11th, 2011 10/11/11 101111 47
November 1st, 2011 11/1/11 11111 31
11/01/11 110111 55
November 10th, 2011 11/10/11 111011 59
November 11th, 2011 11/11/11 111111 63

Here they are in dd/mm/yy format:

Binary Dates in 2011 (dd/mm/yy)
Date dd/mm/yy Binary Decimal
January 1st, 2011 1/1/11 1111 15
1/01/11 10111 23
January 10th, 2011 10/1/11 10111 23
10/01/11 100111 39
January 11th, 2011 11/1/11 11111 31
11/01/11 110111 55
October 1st, 2011 1/10/11 11011 27
October 10th, 2011 10/10/11 101011 43
October 11th, 2011 11/10/11 111011 59
November 1st, 2011 1/11/11 11111 31
November 10th, 2011 10/11/11 101111 47
November 11th, 2011 11/11/11 111111 63

And in case you were wondering, 2010 = 11111011010 in binary, and 2011 = 11111011011 in binary.

(If this blog existed in 2000 — if blogs existed in 2000 period — I would have made tables for the years 2000 and 2001 as well.)

## Palindromes

Considering dates as numbers leads you to wonder which are number palindromes. Numbers written with leading zeros are not palindromes, so numbers ending with zeros are not palindromes either. This means no dates in 2010 are palindromic. In 2011 however, there are palindromic dates. There are several consisting of all 1s, like 1/1/11, but those are not interesting. That leaves two palindromic dates made up of both 0s and 1s:

• January 10th, 2011, in mm/dd/yy format: 1/10/11.
• October 1st, 2011, in dd/mm/yy format: 1/10/11.

Both are the same binary number: 11011 (27 decimal).

## Binary Times

People have also been tweeting about binary times. There are binary times every day, but they’ll seem more significant on binary days. There are 12, not including seconds and duplicates for AM/PM: 1:00, 1:01, 1:10, 1:11, 10:00, 10:01, 10:10, 10:11, 11:00, 11:01, 11:10, 11:11. (I’ll leave it as an exercise to compute these as decimal values.)

Now having thrown time into the mix, we can consider some new palindromes. For example, 1/1/10 (mm/dd/yy) at 1:11 AM is 1110111.

1. You do love binary more than I do. Wait, can one love something more than someone else? Love is love. Computer programmer have gotten away from the machine thanks to the modern programming environments… they collect our garbage, they utilize memory on our behalf and save us from ourselves, they hold our hand… I suppose that’s okay, but I still have a soft spot for reading a 6502 machine code book and writing programs in hex, counting jump offsets by hand.

2. I still look upon “peek” and “poke” fondly.

3. Hugh Jackman says:

I am a Pastor preparing my sermon for Sunday Service, your blog really helped me, looks like tis Binary thing may attract more attention than you may imagine…

4. Lenore says:

Love It! Thanks!!! I am going to use this for a math lesson in 6th grade.

5. @Hugh: Thanks. I’d be interested in how you incorporated “binary” into your sermon.

@Lenore: Thanks. Let me know how it turns out. I’ve been wondering what the best grade is in which to introduce binary.

6. serene says:

this is so cool, thanks for laying it out…my b-day is today 01/10/10 and I’m turning 26 so thanks again for the info!

7. @serene: Your 27th birthday — 1/10/11 — will also “match”: 11011 = 27 (and 11011 is also palindromic as I noted above).

8. Yesterday, 1/10/10, my stats report says this article was viewed 101 times:

You gotta love it!

9. Cris says:

My daughter’s birthday is 1-11-11
Does this mean anything?
Thank you

10. Cris,

To me it’s just a cool looking number (it’s even cooler if she’s going to be 1 or 10 or 11!).

11. Just for fun, and ’cause I have nothing better to do I have made a countdown to 10/10/10 10:10am and 10 seconds.

12. Pingback: BINARY DAY
13. Tom says:

On 11/10/10 I will be 111010 years old! Happy Binary, y’all!

14. Haaaaleee says:

Happy Binary day fellow nerds

15. ŠiK says:

Cherish the binary day ! After tomorrow there are only 9 left in your lifetime.

16. These were my stats from yesterday, 1/1/11:

17. Sasha says:

My daughter will be 11 on the 11/1/11 does that mean anything 1111111

18. Sasha,

All I know is that 1111111 is 127 in decimal.

19. Pattermomma says:

I was up checking the school closings list, wondering what my 9 year old son could occupy himself with today, and Googled “Binary Code Day.” Now I can’t wait for him to get up so I can show him your site! (I think Patterdad taught him Binary in third grade.)

20. I was a numbers geek first, then an arithmetic geek, and eventually a full-blown mathematics geek. I discovered binary in a math book that I checked out from the library when I was seven. I thought it was cool that on my next birthday I would turn from one hundred eleven years old (0111) to one thousand (1000)! By the end of that year, everyone on my block knew the basics of counting by twos. I am sure most of them quickly forgot it but I grew up to be a master computer programmer.

21. @TIME NewsFeed,

There’s only ONE math whiz here 😉 .

22. Tom Snyder says:

NOW go figure this out…. Take the last 2 digits of the year you were born plus the age you will be this year and it WILL EQUAL …. 111!

THE STRANGE THING IS……NO MATTER HOW YOU DO IT IT’S STILL 111.

23. @Tom Snyder,

In 2010 it would have equaled 110, and in 2001 it would have equaled 101. But all the years in between — and before and after — are non-binary looking.

24. Jessop says:

I’m surprised I’m the first one to point this out, to the extent that I suspect I’m making a mistake, but if you take the separate components of the first of October in the DD/MM/YY format, ’01 10 11′, then you’ve got the first three binary numbers ‘1 2 3’.

Which also happened on the 10th of January this year in the MM/DD/YY format (01/10/11), but only happens twice every hundred years, and won’t happen again until the 10th of January 2111.

Which seems interesting to me.

25. @Jessop,

Your math is correct. I never noticed that pattern.

26. Dan Kinobi says:

How cool would it be if you were 63 on 11/11/11!!!

I wonder if any people born on those days realise the immensity of their birthday! 😉

27. Charlie says:

@Tom

The last 2 digits of the year you were born plus your current age will always bring you to the current year… an extra 100 if you were born in the previous century.

Numbers are cool. Binary numbers are soothingly simple and very useful.

Today is a binary day – 11/10/11 and tomorrow is the last of the century 11/11/11 … sniff. I’ll miss you my little friends. I will counts the minutes in your absence. Ha ha !

Thank you God for your number system !

28. Hoo..woo… Today is the last binary date of this century…
Thank god, I am still alive…
Its so sad we will never meet these dates again 🙁

29. Mayur Kubavat says:

Today’s Date – 11/11/2011

111111×111111 = 12345654321

How Cool is that!
Happy Binary Day

Enjoy…

30. Michelle says:

My son was born 10/01/10 at 10.17

31. dermot says:

i was born 04/04/1972 and my first child was born 11/11/2010….thus weird!?

32. Plaok says:

i hate binary dates so much. it’s stupid

33. @Plaok,

Well I guess it’s good that it will be 88 years until the next one then! But do me a favor — if you’re around to see it, please have a toast in my honor :).

34. Allan says:

There are only 10 types of people in the world, those who understand binary and those who don’t.