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=== | === Article of the Week <font size=1>[ [[CZ:Article of the Week|about]] ]</font> === | ||
[[Image: | [[Image:Prime rectangles.png|200px|right]] | ||
'''[[ | A '''[[prime number]]''' is a number that can be evenly divided by exactly two positive [[integer|whole numbers]], namely 1 and itself. The first few prime numbers are 2, 3, 5, 7, 11, 13, and 17. A prime number <math>p</math> cannot be factored as the [[multiplication|product]] of two numbers <math>\scriptstyle p=a\times b,</math> except for the trivial factorizations <math>\scriptstyle p = 1\times p = p\times 1</math> that all numbers possess. | ||
=== New Draft of the Week <font size=1>[ [[CZ:New | With the exception of 2, all prime numbers are odd numbers, but not every odd number is prime. For example, <math>\scriptstyle 9 = 3\times 3</math> and <math>\scriptstyle 15 = 3\times 5,</math> so neither 9 nor 15 is prime. By the strict mathematical definition, the number 1 is not considered to be prime (although this is a matter of definition, and mathematicians in the past often did consider 1 to be a prime). <font size=1>[[Prime number|['''more...''']]]</font> | ||
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=== New Draft of the Week <font size=1>[ [[CZ:New Draft of the Week|about]] ]</font> === | |||
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The '''[[Red Sea Urchin]]''', ''Strongylocentrotus franciscanus'' (A. Agassiz, 1863), is a species of marine invertebrate belonging to the phylum [[Echinodermata]] or "spiny-skinned" animals. Typically found in the Pacific ocean from Alaska to Baja California, red urchins inhabit shallow waters from the low-tide line to depths of 100 m. In general, this species prefers wave-sheltered rocky shorelines. <font size=1>[[Red Sea Urchin|['''more...''']]]</font> | |||
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Article of the Week [ about ] A prime number is a number that can be evenly divided by exactly two positive whole numbers, namely 1 and itself. The first few prime numbers are 2, 3, 5, 7, 11, 13, and 17. A prime number cannot be factored as the product of two numbers except for the trivial factorizations that all numbers possess. With the exception of 2, all prime numbers are odd numbers, but not every odd number is prime. For example, and so neither 9 nor 15 is prime. By the strict mathematical definition, the number 1 is not considered to be prime (although this is a matter of definition, and mathematicians in the past often did consider 1 to be a prime). [more...] New Draft of the Week [ about ] The Red Sea Urchin, Strongylocentrotus franciscanus (A. Agassiz, 1863), is a species of marine invertebrate belonging to the phylum Echinodermata or "spiny-skinned" animals. Typically found in the Pacific ocean from Alaska to Baja California, red urchins inhabit shallow waters from the low-tide line to depths of 100 m. In general, this species prefers wave-sheltered rocky shorelines. [more...] | |||||||||||||
