why are there only 28 days (or 29 in a leap year)in February, and not 30 or 31?
92608
oh i just found this out, visit my source, it describes in perfectly.
109867
Here is a poem to help you learn how many days in a month\n\nThirty days hath September,\nApril, June, and November;\nAll the rest have thirty-one,\nExcepting February alone,\nWhich hath but twenty-eight, in fine,\nTill Leap Year gives it twenty-nine.
606654
PRecisely 365.24 days. Every four years we have a leap year, but to keep from getting ahead we skip the whole leap year thing once out of every hundred. We might have done so in 2000, I don't remember.
239998
for 30 days its : 43,200 minutes\nfor 31 days its : 44,640 minutes\nand for 28 days its : 40,320 minutes\nand for leap month (29 days) its: 41,760 minutes
39487
Many, it depends.\nIn a non leap year of 365 days the number of seconds is:\n365 * 24 * 60 * 60 = 31,536,000\nIn a leap year the answer is 31,622,400\nIn a solar year (of 365.2422 days) it is 31,556,926.08 secnds.\nBut in a sidereal year and also a lunar year it is again different.\n\nYet another different answer is that are only 12 secnds a year. January second, February second, March second, etc...
1085792
It has occurred on \n\nAugust 1st, 2000, \nAugust 1st, 1995,\nAugust 1st, 1989,\nAugust 1st, 1978\n\nIt will always happen every 28 years. 28 years represents 7 days of the week X 4 years between leap years.
410640
Actually, the easiest way to look at it is that the person was born on the day after February 28.  So, it does not matter if it's leap year or not, the person celebrates another year of life on the day after Feb. 28 whether it's Feb 29 or March 1.\nNow, if the person is a woman who stops counting years after the age of 29, then it's probably easier to only county your birthday every 4 years ;-)
565155
Every months have 28 days.
171415
It is the 267th day of this year. On a leap year it would be the 268th day.
84324
A widely believed--but possibly erroneous--story has it that February is so short because the Romans borrowed a day from it to add to August. August was originally a 30-day month called Sextilis, but it was renamed to honor the emperor Augustus Caesar, just as July had earlier been renamed to honor Julius Caesar. Naturally, it wouldn't do to have Gus's month be shorter than Julius's, hence the switch.\n\nBut some historians say this is bunk. They say February has always had 28 days, going back to the 8th century BC, when a Roman king by the name of Numa Pompilius established the basic Roman calendar. Before Numa was on the job the calendar covered only ten months, March through December. December, as you may know, roughly translates from Latin as "tenth." July was originally called Quintilis, "fifth," Sextilis was sixth, September was seventh, and so on.\n\nTo meticulous persons such as ourselves, Randy, having the calendar run out in December and not pick up again until March probably seems like a pretty casual approach to timekeeping. However, we must realize that 3,000 years ago, not a helluva lot happened between December and March. The Romans at the time were an agricultural people, and the main purpose of the calendar was to govern the cycle of planting and harvesting.\n\nNuma, however, was a real go-getter-type guy, and when he got to be in charge of things, he decided it was going to look pretty stupid if the Romans gave the world a calendar that somehow overlooked one-sixth of the year. So he decided that a year would have 355 days--still a bit off the mark, admittedly, but definitely a step in the right direction. Three hundred fifty five days was the approximate length of 12 lunar cycles, with lots of leap days thrown in to keep the calendar lined up with the seasons. Numa also added two new months, January and February, to the end of the year. Since the Romans thought even numbers were unlucky, he made seven of the months 29 days long, and four months 31 days long.\n\nBut Numa needed one short, even-numbered month to make the number of days work out to 355. February got elected. It was the last month of the year (January didn't become the first month until centuries later), it was in the middle of winter, and presumably, if there had to be an unlucky month, better to make it a short one.\n\nMany years later, Julius Caesar reorganized the calendar yet again, giving it 365 days. Some say he made February 29 days long, 30 in leap year, and that Augustus Caesar later pilfered a day; others say Julius just kept it at 28. None of this changes the underlying truth: February is so short mainly because it was the month nobody liked much--a judgment with which I heartily concur. Frankly, if the Romans had cut it down to 15 minutes, it wouldn't have bothered me a bit.
1068494
350,000 days = 958 non-leap years, 330 days.\n\nThere will be 240 "February 29th's" during that time (those extra days get subtracted from the 330 days).\n\nSo, in 350,000 days, it will be September 13, 2964.
700155
Leap year.\n\nA leap year has 366 days.
213206
A leap year is a year with one extra day inserted into February, the leap year is 366 days with 29 days in February as opposed to the normal 28 days. (There are a few past exceptions to this) \n\nLeap years are needed so that the calendar is in alignment with the earth's motion around the sun. \n\nIt takes 365.2422 days for the earth to make one revolution around the sun (the time is takes to orbit the sun).\n\nUsing a calendar with 365 days would result in an error of 0.2422 days or almost 6 hours per year. After 100 years, this calendar would be more than 24 days ahead of the seasons (tropical year), which is not a desirable situation. It is desirable to align the calendar with the seasons, and make the difference as small as possible.\n\nBy adding leap years approximately every 4th year, this difference between the calendar and the seasons can be reduced significantly, and the calendar will follow the seasons much more closely than without leap years.
53606
Officially 365.24. But there are 365 days in a regular Gregorian year, 366 in a leap year. Leap Years only come around every 4 years, but a the turn of every odd numbered century (1900, 2100 etc.), there is no leap year. Without leap years, the .24 at the end of each year would throw the seasons out of place over time
774003
.... except February alone which has 28 days clear and 29 in each leap year.
810204
As some answerers have commented, the best way to avoid the leap year problem is to use the actual value for the number of days in a year determined by the earth's orbit, not that arbitrarily assigned by a calendar. The best value to use for calendar purposes seems to be 365.2424days (see the Wikipedia article on Tropical Year for a very detailed discussion!) and so the number of seconds in a decade is 315569433.6.
624024
Days in a year = 365 except in a Leap Year when there Arte 366 (29th February added). A Leap Year is when the date is divisible by 4 so we'll get one in 2008.\n\nIf you are counting the dates you quote as inclusive then you've got\n\n28/29/30th in September = 3\nOctober has 31\nNovember has 30\nDecember has 31\nJanuary has 31\nFebruary has 28\nMarch has 31\nApril has 30\nMay has 31\nJune has 30\nJuly has 31\nThen you've got 16 in August\n\nTogether you have 323 inclusive.\n\n24 continuous months is just that a period of two years from the start of any month such as 1st August 1989 to 31st July 1991.