Tall-leksikon - Matematikk på nett - Nordreisa videregående skole

Dagens tall:
2004
• Faktorisering: 2004 = 2⋅
2⋅
3⋅167
• Partall
• Pytagoreisk tall – men ikke primitivt – f.eks.:
2
2
2
1503 + 2004 = 2505
2
2
2
2004 + 2672 = 3340
2
2
2
835 + 2004 = 2171
• Året 2004, etter vår tidsregning: Vi følger den gregorianske kalenderen. The
calendar currently in worldwide use for secular purposes based on a cycle of 400 years comprising 146,097 days, giving a year
of average length 365.2425 days. The Gregorian calendar is a modification of the Julian calendar in which leap years are
omitted in years divisible by 100 but not divisible by 400. By this rule, the year 1900 was not a leap year (1900 is
divisible by 100 and not divisible by 400), but the year 2000 will be a leap year (2000 is divisible by 400). The total number
of days in 400 years is therefore given by 400 ⋅365+ 100 − 3 = 146097 This also gives an exact number of
146097 / 7 = 20871weeks
per 400-year cycle. The Gregorian calendar was constructed to give a close approximation to the
tropical year, which is the actual length of time it takes for the Earth to complete one orbit around the Sun. The Protestant
German countries adopted the Gregorian reform in 1700. By this time, the calendar trailed the seasons by 11 days. England
(and the American colonies) finally followed suit in 1752, and Wednesday, September 2, 1752 was immediately followed by
Thursday, September 14, 1752. This traumatic change resulted in widespread riots and the populace demanding "Give us the
eleven days back!"
September 1752
Su M Tu W Th F Sa
&; &; 1 2 14 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29 30
Sweden followed England's lead in 1753. Russia, however, did not follow suit until 1918, when January 31, 1918 was
immediately followed by February 14th. In fact, however, the USSR is not on the Gregorian calendar, but on a more accurate
one of their own devising. The USSR calendar is designed to more closely approximate the true length of the tropical year, thus
has one additional rule for when a year is a leap year. It will remain in synchronization with the Gregorian calendar for
thousands more years, by which time one or both will have probably fallen into disuse. Similarly, Iranian calendar is also a
more accurate version of the Gregorian calendar (Ross).
http://matematikk/matematikk/kalmat.htm
http://scienceworld.wolfram.com/astronomy/GregorianCalendar.html
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