Numbers 220-229

A page of the Numeropedia - the Special Encyclopedia of Numbers

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220 (separate page)

221

[History]   The year China united (221 B.C.E.) when the king Qin Shi Huang (221-210 B.C.) (of the Qin/Chin) defeated other 6 kingdoms.

[Math.]  25,986 = 213×122 and backward 312×221 = 68,952.

[Math.]  Reversible numbers and their squares: 1222 = 14884 and 2212 = 48841.

[Phone]  International telephone dialing code for Senegal.

[Sport]  Playoff series “best of five” is usually in 2-2-1 format, where five games are played in alternating courts, starting with the home court of the team of better record.

222

[Math.]  Three square numbers using the same digits: 2072 = 42849, 2222 = 49284 and 2882 = 82944.

[Math.]  All the cubic powers 23 = 8, 223 = 10,648, 2223 = 10,941,048, 22223 = 10,970,645,048, 22,2223 = 10,973,607,685,048 and 222,2223 = 10,973,903,978,085,048 do not use digits 2.

[Movie]  A 70’s TV series “Room 222”.

[Phone]  The number to key in text messaging on telephone keypad for letter C.

[Phone]  International telephone dialing code for the Mauritania.

[World]  The ISO country code for El Salvador. (ISO-3166)

223

[Astronomy] The number of synodic months (exactly) in a Saros cycle (used to calculate the solar and lunar eclipses): 6585 days 7 hours 23 minutes, approximately 19 eclipse years (6585.78 days = 6585 days 18 hours 43.2 minutes).

[Math.]  A prime number.

223

[Math.]  Numbers of the same pattern, xxy, where y = x +1: 1122 = 012,544 & 012+544 = 556 & 5562 = 309,136 & 309+136 = 445 & 4452 = 198,025 & 198+025 = 223 & 2232 = 049,729 & 049+729 = 778 & 7782 = 605,284 & 605+284 = 889 & 8892 = 790,321 & 790+321 = 1111. Also: 3342 = 111556 & 111+556 = 667.

[Phone]  International telephone dialing code for the Mali.

[Tech.]  A 223-caliber or .223-caliber bullet.

224

[Measure]  The number of oz (ounces) in a stone.

British imperial units for weight measures: 1 stone = 14 lb (pounds) = 224 oz (ounces) = 3584 drams = 98,000 grains = 6350.29318 g (grams) & 1 grain = 64.79891 mg (milligrams) & 1 ounce = 16 drams = 437.5 grains & 1 dram = 2711/32 grains.

[Phone]  International telephone dialing code for the Guinea.

[Tech.]  The hash functions recommended and approved by NIST to replace SHA-1, which outputs 160 bits hash: SHA-512, SHA-384, SHA-256 and SHA-224. All 3-digit number indicates the number of output bits.

224 & 226

[Math.]  Squares of 2 consecutive even numbers using the same digits: 2242 = 50176 and 2262 = 51076.

225

[Game]  The number of squares on a Scrabble board (15×15). There are 100 numbered letter tiles used in the game and 7 letters on each player’s rack at a time.

[Math.]  Sum of the first 5 cube numbers: 13+23+33+43+53 = 225 = (1+2+3+4+5)2.

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

[Math.]  Inserting 72 between 2 digits 2 in the square number 225 = 152 and repeatedly inserting numbers 72 between the digits 7 and 2 yields other squares 27225 = 1652, 2772225  = 16652, 277722225 = 166652, 27777222225 = 1666652, 2777772222225 = 16666652

[Phone]  International telephone dialing code for Ivory Coast (Côte d’Ivoire).

[Tech.]  Automobile tires used in the U.S. have tire section width of 145, 155, 165, 175, 185, 195, 205, 215, 225, 235, 245 or 255 (millimeters).

226

[Phone]  International telephone dialing code for Burkina Faso.

[World]  The ISO country code for Equatorial Guinea. (ISO-3166)

227

[Phone]  International telephone dialing code for Niger.

228

[Calendar]  On average, 19 solar years (228 solar months) is almost exactly 235 lunar months, approximately: 19´365.2422 = 6939.6018 and 235´29.53 = 6939.55, (but also was given 6939.6884). It is called Metonic cycle, when all the phases of waxing and waning moon fall on the same days of the weeks for the whole solar year.

[Phone]  International telephone dialing code for Togo.

229

[Math.]  A prime number.

[Math.]  The sum of number 299 and its reversal is also prime: 229+922 = 1151.

[Math.]  Three square numbers using the same digits: 1122 = 12544, 2112 = 44521 and 2292 = 52441.

[Phone]  International telephone dialing code for Benin.

[Phone]  The smallest prime number assigned for an NANPA/U.S. telephone area code: for Georgia (Albany). As of 2005.

220-229

[Library]  Numbers 200-299 are the first 3 digits in Dewey Decimal Classification System call numbers for library books in Religion and Theology. Numbers 220-229 are for books in Bible.

200-299

[Education]   The numbers commonly assigned for graduate courses in most U.S. universities and colleges.