Tall-leksikon - Matematikk på nett - Nordreisa videregående skole
Tall-leksikon - Matematikk på nett - Nordreisa videregående skole
Tall-leksikon - Matematikk på nett - Nordreisa videregående skole
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Dagens tall:<br />
• Primtall, faktorene 1 og 7<br />
7<br />
(From Wikipedia, the free encyclopedia)<br />
• Ulike former: VII – romertall, ፯ - amarisk, ٧ – arabisk, ৭ – bengalsk, 七,柒 – kinesisk, ७ –<br />
devanagarisk, ז – hebraisk, ៧ - khmar, ๗ – thai<br />
• Forstavelse hepta- eller hept- fra gresk og sept- fra latin<br />
• Binært 111, tretallssystem 21, firetalls 13, femtalls 12, sekstalls 11, sjutalls 10, oktalt 7, tolvtallssystem<br />
7, heksadesimalt 7<br />
• Et natulig tall som leigger mellom 6 og 8. Det minste positive heltallet som uttales med to stavelser <strong>på</strong><br />
engelsk.<br />
Resten er engelsk – tatt direkte fra Wikipedia:<br />
• Seven is the fourth prime number. It is not only a Mersenne prime (since 2 3 − 1 = 7) but also a double<br />
Mersenne prime since it is itself the exponent for another Mersenne prime (127). It is also a Newman-<br />
Shanks-Williams prime, a Woodall prime, a factorial prime, a lucky prime, a happy number, a safe<br />
prime and the fourth Heegner number.<br />
• Seven is the only number less than 15 which cannot be represented as the sum of the squares of three<br />
integers.<br />
• Seven is the aliquot sum of one number, the cubic number 8 and is the base of the 7-aliquot tree. It is<br />
also said to be a lucky number<br />
• n = 7 is the first natural number for which the next statement does not hold: "Two nilpotent<br />
endomorphisms from C n with the same minimal polynomial and the same rank are similar."<br />
• 7 is the only dimension, besides the familiar 3, in which a vector cross product can be defined [citation<br />
needed] .<br />
• 999,999 divided by 7 is exactly 142,857. Therefore, when a vulgar fraction with 7 in the denominator<br />
is converted to a decimal expansion, the result has the same six-digit repeating sequence after the<br />
decimal point, but the sequence can start with any of those six digits. [1] For example,<br />
1/7 = 0.142 857 142.... and 2/7 = 0.285 714 285...<br />
• A seven-sided shape is a heptagon. The regular n-gons for n ≤ 6 can be constructed by compass and<br />
straightedge alone, but the regular heptagon cannot. Figurate numbers representing heptagons<br />
(including seven) are called heptagonal numbers. Seven is also a centered hexagonal number.<br />
• There are seven frieze groups, the groups consisting of symmetries of the plane whose group of<br />
translations is isomorphic to the group of integers.<br />
• There are seven fundamental types of catastrophes.<br />
• Seven is the sum of any two opposite sides on a standard six-sided die. When rolling two standard sixsided<br />
dice, seven has a 6 in 36 (or 1/6th) probability of being rolled (1–6, 6–1, 2–5, 5–2, 3–4, or 4–3),<br />
the greatest of any number.<br />
• The Millennium Prize Problems are seven problems in mathematics that were stated by the Clay<br />
Mathematics Institute in 2000. Currently, six of the problems remain unsolved.<br />
• In the beginning, various Hindus wrote 7 more or less in one<br />
stroke as a curve that looks like an uppercase J vertically<br />
inverted. The western Ghubar Arabs' main contribution was<br />
to make the longer line diagonal rather than straight, though<br />
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