Number 90

A page of the Numeropedia - the Special Encyclopedia of Numbers

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[Calendar]  The number of days of the first quarter (January-March) is either 90 for a non-leap year or 91 for a non-leap year.

[Chemistry]  The atomic number of Thorium (Th). An element in the Actinide series: Actinium (89) to Lawrencium (103).

[Geology]  The 90th parallel (90o latitude line) North (or South) is the North (or South) pole.

[Geology]  I-90, the longest major U.S. West-East interstate highway, connecting Seattle, Washington to Boston, Massachusetts, 3163 miles. It is the longest major U.S. interstate highway.

[Language]  Prefixes : Nonage-

[Library]  ISBN-90 is the International Standard Book Number for books published in Dutch and Flemish.

[Math.]  The right angle or the interior angles of a square are 90o

An acute angle is less than 90o.

An obtuse angle is greater than 90o but less than 180o.

[Math.]  Sum of 2 complementary angles is 90o. sin(a) = cos(90oa); tan(a) = cot(90oa).

[Math.]  sin(0o) = sin(180o) = cos(90o) = cos(270o) = tan(0o) = tan(180o) = cot(90o) = cot(270o) = sinh(0) = tanh(0) = log(1) = 0.

sin(90o) = cos(0o) = tan(45o) = tan(225o) = cot(45o) = cot(225o) = cosh(0) = 1.

[Math.]  90 = 01+12+23+34.

[Math.]  Two consecutive sums of consecutive numbers: 16+17+18+19+20 = 21+22+23+24 = 90.

[Math.]  The infinite sum Sn(1/n4) = p4/90 = z(4), where Sn is the infinite sum which n runs over all positive integers and z(s) is the Riemann zeta function over complex variable s.

[Math.]

1×8+1 = 9

12×8+2 = 98

123×8+3 = 987

1234×8+4 = 9876

12,345×8+5 = 98,765

123,456×8+6 = 987,654

1,234,567×8+7 = 9,876,543

12,345,678×8+8 = 98,765,432

123,456,789×8+9 = 987,654,321

1,234,567,890×8+90 = 9,876,543,210

(start of a new cycle)

12,345,678,901×8+901 = 98,765,432,109

123,456,789,012×8+9,002 = 987,654,321,098

1,234,567,890,123×8+90,003 = 9,876,543,210,987

12,345,678,901,234×8+900,004 = 98,765,432,109,876

123,456,789,012,345×8+9,000,005 = 987,654,321,098,765

1,234,567,890,123,456×8+90,000,006 = 9,876,543,210,987,654

12,345,678,901,234,567×8+900,000,007 = 98,765,432,109,876,543

123,456,789,012,345,678×8+9,000,000,008 = 987,654,321,098,765,432

1,234,567,890,123,456,789×8+90000000009 = 9,876,543,210,987,654,321

12,345,678,901,234,567,890×8+ 900000000090 = 98,765,432,109,876,543,210

... (end of cycle)

[Phone]  International telephone dialing code for Turkey.

[Science]

 American system British system Number ***** quindecillion 1090 quindecillion octillion 1048 octillion ***** 1027

[Sport]  The distance (feet) from base to base (included home plate) in a professional baseball field.

[Sport]  The number of edges on a regular soccer ball (truncated icosahedron), formed by 32 polygon pieces (12 pentagons and 20 hexagons) and a total of 60 vertices.

[Sport]  The regular time (minutes) for an official match of soccer game: two 45-minute halves.

[Tech.]  The “number system” code of an EAN-13 barcode for Austria’s products: 90 and 91.

[Tech.]  Octane (R+M)/2 antiknock index rating of unleaded gasoline for automobiles in the U.S.: 87, 88, 89, 90 and 91.

[Tech.]  The numbers of automobile gear oil SAE viscosity: 75W, 80W, 80W-90, 85W, 90W and 140W.

[Tech.]  The popular Alkaline-Manganese battery voltages for household electronic devices: 1.5V – 3V – 4.5V – 6V – 9V, available in popular sizes: AAA, AA, C, D, G and N. The Carbon-Zinc batteries have additional values: 12V – 22.5V – 45V and 90V. Other values: PP3 – 1.2V – 3.6V – 4.8V – 8.4V for Ni-Cad rechargeables.

[World]  The ISO-3166 country code for Solomon Islands (was British Solomon Islands).

90.2

[Sport]  The isosceles triangle of sides 12-12-17 (inches) at the top of the home plate (whose shape is a non-regular pentagon) in baseball is not quite a right triangle as specified, since 122+122 = 288 < 172 = 289. Its largest angle is an obtuse angle of 90.2o.