# Leap Year?? **URL:** \ **Category:** Factual Questions\ **Created:** [December 27, 1999, 3:18am UTC](https://boards.straightdope.com/t/leap-year/5614 "1999-12-27T03:18:00Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![Czarcasm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/czarcasm/32/4050_2.png) [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)\ **Post date:** [December 27, 1999, 3:18am UTC](https://boards.straightdope.com/t/leap-year/5614/1 "1999-12-27T03:18:00Z")
I have heard conflicting reports and I need to know if the year 2000 is a leap year. Half of my calenders have a February 29, and half don’t! ---
**Author:** ![Ursa\_Major](https://avatars.discourse-cdn.com/v4/letter/u/a88e57/32.png) [@Ursa\_Major](https://boards.straightdope.com/u/Ursa_Major)\ **Post date:** [December 27, 1999, 3:26am UTC](https://boards.straightdope.com/t/leap-year/5614/2 "1999-12-27T03:26:00Z")
2000 has a Feb. 29 because, although it is a century year, it is devisable by 400. Thems the rules. I didn’t write 'em. ---
**Author:** ![G.B.H.Hornswoggler](https://avatars.discourse-cdn.com/v4/letter/g/c67d28/32.png) [@G.B.H.Hornswoggler](https://boards.straightdope.com/u/G.B.H.Hornswoggler)\ **Post date:** [December 27, 1999, 3:29am UTC](https://boards.straightdope.com/t/leap-year/5614/3 "1999-12-27T03:29:00Z")
This is one of those cases where knowing a little can be more dangerous than being completely ignorant. Hoping that isn’t the case with me, here goes… Leap days are added in years divisible by 4 (i.e., 1992, 1996, etc.) _except_ years divisible by 100 (i.e., 1800, 1900, etc.), which have no leap day, \*except[/] years divisible by 400 (i.e., 1600, 2000, etc.) which _do_ have a leap day. So, yes, 2000 will have a February 29th. There is another correction on an even longer period (4000 years, IIRC), but we won’t have to worry about that for a while. It all has to do with the inconvenient fact that the earth’s orbital period (year) is not a simple multiple of its rotational period (day). Of course, there’s no reason for the two to be correlated at all. And I think there was a thread in the recent past that covered all this, so if the search engine only worked, you could’ve looked it up. But it doesn’t, so you couldn’t. * * * …but when you get blue, and you’ve lost all your dreams, there’s nothing like a campfire and a can of beans! ---
**Author:** ![dlv](https://avatars.discourse-cdn.com/v4/letter/d/5f9b8f/32.png) [@dlv](https://boards.straightdope.com/u/dlv)\ **Post date:** [December 27, 1999, 3:58am UTC](https://boards.straightdope.com/t/leap-year/5614/4 "1999-12-27T03:58:00Z")
Here’s an interesting Y2K story. I used to be responsible for a large C program written by a guy who really wasn’t a programmer. We hired a contractor to do a Y2K check on it, and he found a bug! It used the following logic to decide if a year is leap: **If the year is divisible by 4 and the year is not divisible by 100 then the year has Feb 29th.** So, it would have worked correctly in 1900 and 2100 (as if anyone cares) but it would have been off by a day in Y2K. ---
**Author:** ![system](https://global.discourse-cdn.com/straightdope/original/2X/e/e489c3b7d8fce19c4b355dd4fc3f88cc39c34b87.png) [@system](https://boards.straightdope.com/u/system)\ **Post date:** [December 27, 1999, 4:09am UTC](https://boards.straightdope.com/t/leap-year/5614/5 "1999-12-27T04:09:00Z")
Here’s a site that explains it: [http://155.135.31.26/oliver/smt310-handouts/calendar.htm](http://155.135.31.26/oliver/smt310-handouts/calendar.htm) * * * Sue from El Paso Experience is what you get when you didn’t get what you wanted. ---
**Author:** ![C\_K\_Dexter\_Haven](https://avatars.discourse-cdn.com/v4/letter/c/b2d939/32.png) [@C\_K\_Dexter\_Haven](https://boards.straightdope.com/u/C_K_Dexter_Haven)\ **Post date:** [December 27, 1999, 2:17pm UTC](https://boards.straightdope.com/t/leap-year/5614/6 "1999-12-27T14:17:00Z")
Here’s yet another reference: [Why do we have leap years?](http://www.straightdope.com/mailbag/mleapyr.html) ---
**Author:** ![Czarcasm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/czarcasm/32/4050_2.png) [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)\ **Post date:** [December 28, 1999, 12:28am UTC](https://boards.straightdope.com/t/leap-year/5614/7 "1999-12-28T00:28:00Z")
Thanks for the help everyone, especially Sue. I _did_ try to do an archive search(useless!), and a news report mistakenly reported that it wasn’t a leap year. ---
**Author:** ![John\_W.Kennedy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_w.kennedy/32/1031_2.png) [@John\_W.Kennedy](https://boards.straightdope.com/u/John_W.Kennedy)\ **Post date:** [December 29, 1999, 6:38am UTC](https://boards.straightdope.com/t/leap-year/5614/8 "1999-12-29T06:38:00Z")
People frequently screw up. Over the years, I’ve seen a distressing number of programs that said, “If the last digit of the year is divisible by four, it’s a leap year,” which, of course, was blowing up both the first time I encountered it (in 1970) and the next time (in 1990). * * * John W. Kennedy “Compact is becoming contract; man only earns and pays.” – Charles Williams ---
**Author:** ![Boris\_B](https://avatars.discourse-cdn.com/v4/letter/b/fbc32d/32.png) [@Boris\_B](https://boards.straightdope.com/u/Boris_B)\ **Post date:** [December 29, 1999, 6:42am UTC](https://boards.straightdope.com/t/leap-year/5614/9 "1999-12-29T06:42:00Z")
I’ll point out the bit of trivia I point out every time this comes up. This is the first time the 400-year exception-to-the-exception has ever come up in North America, and only the second time it has come up since the invention of the Gregorian Calendar. So it’s only to be expected that it’s a little unfamiliar. ---
**Author:** ![torq](https://avatars.discourse-cdn.com/v4/letter/t/dfb087/32.png) [@torq](https://boards.straightdope.com/u/torq)\ **Post date:** [December 28, 1999, 9:16pm UTC](https://boards.straightdope.com/t/leap-year/5614/10 "1999-12-28T21:16:00Z")
Actually, it’s an exception (LY if divisible by 400) to an exception (not LY if divisible by 100) to an exception (LY if divisible by 4) of the rule (365 days/year). I’ve never seen anyone mention the 100 year exception-squared without also mentioning the 400 year exception-cubed, so I was frankly pretty skeptical about the whole problem. I’m amazed that someone actually ran into a program where the programmer knew about one but not the other.