# Leap Years

ThudanBlunder
Posers and Puzzles 12 Aug '06 13:13
1. 12 Aug '06 13:13
How many leap years have there been since the Union Jack was adopted as the national flag of Great Britain?
2. XanthosNZ
Cancerous Bus Crash
12 Aug '06 14:05
Taking the date of the Union Jack adoption to be 1801 (An earlier version was used to represent England + Scotland from 1606 but that isn't all of GB) we find that we have leap years from 1804 to 2004. So that would be 51 leap years. EXCEPT that 1900 was not a leap year as years divisible by 100 are not leap years unless they are divisible by 400 (1900 was not, 2100 will not, 2000 was).

So 50.
3. 12 Aug '06 15:10
OK, you have got the idea - which was that there are only 97 leap years per 400 years, not 100.
4. AThousandYoung
12 Aug '06 23:32
Originally posted by XanthosNZ
Taking the date of the Union Jack adoption to be 1801 (An earlier version was used to represent England + Scotland from 1606 but that isn't all of GB) we find that we have leap years from 1804 to 2004. So that would be 51 leap years. EXCEPT that 1900 was not a leap year as years divisible by 100 are not leap years unless they are divisible by 400 (1900 was not, 2100 will not, 2000 was).

So 50.
Why does that rule exist (re: years ending in 00)?
5. XanthosNZ
Cancerous Bus Crash
12 Aug '06 23:50
Originally posted by AThousandYoung
Why does that rule exist (re: years ending in 00)?
A year is 365.242375 days long (not 365.25 as most people think). Therefore having a leap year every four years would get us out of sync.
6. 12 Aug '06 23:581 edit
Originally posted by AThousandYoung
Why does that rule exist (re: years ending in 00)?
And there are three rules, not two. In the future they might have to invent a fourth.
7. sonhouse
Fast and Curious
13 Aug '06 05:52
Originally posted by ThudanBlunder
And there are three rules, not two. In the future they might have to invent a fourth.
Already we know about leap seconds, because the earth does not rotate at a totally steady rate, some years it slows down a bit and other years it speeds up so that will throw everything off in due time.
8. 15 Aug '06 22:14
The three rules the Gregorian Calendar uses to define leap years approximate the number of days in a years as:

365 + 1/4 - 1/100 + 1/400
which is equal to 365.2425

Currently there are approximately 365.242375 days in a year, which suggests that we will be 1 day out in 8000 years time. However the number of days in a year is changing and is not predictable, so other fudge factors may be needed before then.
9. sonhouse
Fast and Curious
16 Aug '06 13:01
Originally posted by Fat Lady
The three rules the Gregorian Calendar uses to define leap years approximate the number of days in a years as:

365 + 1/4 - 1/100 + 1/400
which is equal to 365.2425

Currently there are approximately 365.242375 days in a year, which suggests that we will be 1 day out in 8000 years time. However the number of days in a year is changing and is not predictable, so other fudge factors may be needed before then.
Somehow I don't think we will be worrying about that in 8000 years!
10. 17 Aug '06 10:39
Originally posted by sonhouse
...because the earth does not rotate at a totally steady rate, .... other years it speeds up so that will throw everything off in due time
I don't think it spins that fast! ðŸ˜‰
11. 19 Aug '06 10:54
You guys have no lives!!!!!