809的平方根等於多少
⑴ 根號1至100的化簡
根號1至100的化簡如下表：
根號書寫規范：
被開方的數或代數式寫在符號左方v形部分的右邊和符號上方一中團橫部分的下方共同包圍的區域中，而且不能出界，若被開方的數或代數式過長，則上方一橫必須延長確保覆蓋下方的被開方數或代數式。
開n次方的n寫在符號√￣的左邊，n=2（平方根）時n可以忽略不寫，但若是立方根（三次方根）、四次方根等，是必須書寫。
(1)809的平方根等於多少擴展閱讀：
二次根式化簡的基本技巧和方法：
1、根號下是一個正整數
將該數字拆分唯租成一個完全平方數和某個數字的乘積，然後將完全平方數開平方放到根號外面。
2、根號下是一個分數
將該分數拆分成一個分數的平方數和某個數字的乘積，然後將分數開根號到根號外面。
3、根號下有數字和字母
這種情況下，由於不確定字母指培兆是正數還是負數，因此開放的時候要帶著絕對值開方。
4、兩個根式相加減
首先將兩個根式通分，然後再運算。
5、兩個根式相乘除
注意觀察兩個式子的特點，決定先化簡再乘除，還是先乘除再化簡。
⑵ 809是誰的平方
809顯然不慶悄是完全平方數
而且就是一個質數
所以數字昌差手809
就是正負耐嫌根號809的平方
使用計算器可以得到
809約等於正負28.443的平方
⑶ 1到100的平方根
1到100的平方根從1到100按照如下順序：
平方根，又叫二次方根，表示為〔√￣〕，其中屬於非負數的平方根稱之為算術平方根。
一個正數有兩個實平方根，它們互為相反數；0隻有一個平方根，就是0本身；負數有兩個共軛的純虛平方根。
(3)809的平方根等於多少擴展閱讀：
一般地說，若一個非負數x的平方等於a，即x²=a，則這個數x叫做a的算術平方根。
根號的產生源於正方形的對角線長度「根號二」，這個 「根號二」的發現 一度引起了畢達哥拉斯學派的恐慌。因為按當時的權威解釋，萬物皆數。
對於這個無理數「根號二」，最終人們選取了用根號來進行表示。
⑷ 求平方根與立方根表
呵呵
方根：
√0 = 0（表示根號0等於0，下同）
√1 = 1
√2 = 1.4142135623731
√3 = 1.73205080756888
√4 = 2
√5 = 2.23606797749979
√6 = 2.44948974278318
√7 = 2.64575131106459
√8 = 2.82842712474619
√9 = 3
√10 = 3.16227766016838
√11 = 3.3166247903554
√12 = 3.46410161513775
√13 = 3.60555127546399
√14 = 3.74165738677394
√15 = 3.87298334620742
√16 = 4
√17 = 4.12310562561766
√18 = 4.24264068711928
√19 = 4.35889894354067
√20 = 4.47213595499958
√21 = 4.58257569495584
√22 = 4.69041575982343
√23 = 4.79583152331272
√24 = 4.89897948556636
√25 = 5
√26 = 5.09901951359278
√27 = 5.19615242270663
√28 = 5.29150262212918
√29 = 5.3851648071345
√30 = 5.47722557505166
√31 = 5.56776436283002
√32 = 5.65685424949238
√33 = 5.74456264653803
√34 = 5.8309518948453
√35 = 5.91607978309962
√36 = 6
√37 = 6.08276253029822
√38 = 6.16441400296898
√39 = 6.2449979983984
√40 = 6.32455532033676
√41 = 6.40312423743285
√42 = 6.48074069840786
√43 = 6.557438524302
√44 = 6.6332495807108
√45 = 6.70820393249937
√46 = 6.78232998312527
√47 = 6.85565460040104
√48 = 6.92820323027551
√49 = 7
√50 = 7.07106781186548
√51 = 7.14142842854285
√52 = 7.21110255092798
√53 = 7.28010988928052
√54 = 7.34846922834953
√55 = 7.41619848709566
√56 = 7.48331477354788
√57 = 7.54983443527075
√58 = 7.61577310586391
√59 = 7.68114574786861
√60 = 7.74596669241483
√61 = 7.81024967590665
√62 = 7.87400787401181
√63 = 7.93725393319377
√64 = 8
√65 = 8.06225774829855
√66 = 8.12403840463596
√67 = 8.18535277187245
√68 = 8.24621125123532
√69 = 8.30662386291807
√70 = 8.36660026534076
√71 = 8.42614977317636
√72 = 8.48528137423857
√73 = 8.54400374531753
√74 = 8.60232526704263
√75 = 8.66025403784439
√76 = 8.71779788708135
√77 = 8.77496438739212
√78 = 8.83176086632785
√79 = 8.88819441731559
√80 = 8.94427190999916
√81 = 9
√82 = 9.05538513813742
√83 = 9.1104335791443
√84 = 9.16515138991168
√85 = 9.21954445729289
√86 = 9.2736184954957
√87 = 9.32737905308882
√88 = 9.38083151964686
√89 = 9.4339811320566
√90 = 9.48683298050514
√91 = 9.53939201416946
√92 = 9.59166304662544
√93 = 9.64365076099295
√94 = 9.69535971483266
√95 = 9.74679434480896
√96 = 9.79795897113271
√97 = 9.8488578017961
√98 = 9.89949493661167
√99 = 9.9498743710662
√100 = 10
√101 = 10.0498756211209
√102 = 10.0995049383621
√103 = 10.1488915650922
√104 = 10.1980390271856
√105 = 10.2469507659596
√106 = 10.295630140987
√107 = 10.3440804327886
√108 = 10.3923048454133
√109 = 10.4403065089106
√110 = 10.4880884817015
√111 = 10.5356537528527
√112 = 10.5830052442584
√113 = 10.6301458127347
√114 = 10.6770782520313
√115 = 10.7238052947636
√116 = 10.770329614269
√117 = 10.816653826392
√118 = 10.8627804912002
√119 = 10.9087121146357
√120 = 10.9544511501033
√121 = 11
√122 = 11.0453610171873
√123 = 11.0905365064094
√124 = 11.13552872566
√125 = 11.1803398874989
√126 = 11.2249721603218
√127 = 11.2694276695846
√128 = 11.3137084989848
√129 = 11.3578166916005
√130 = 11.4017542509914
√131 = 11.4455231422596
√132 = 11.4891252930761
√133 = 11.5325625946708
√134 = 11.5758369027902
√135 = 11.6189500386223
√136 = 11.6619037896906
√137 = 11.7046999107196
√138 = 11.7473401244707
√139 = 11.7898261225516
√140 = 11.8321595661992
√141 = 11.8743420870379
√142 = 11.916375287813
√143 = 11.9582607431014
√144 = 12
√145 = 12.0415945787923
√146 = 12.0830459735946
√147 = 12.1243556529821
√148 = 12.1655250605964
√149 = 12.2065556157337
√150 = 12.2474487139159
√151 = 12.2882057274445
√152 = 12.328828005938
√153 = 12.369316876853
√154 = 12.4096736459909
√155 = 12.4498995979887
√156 = 12.4899959967968
√157 = 12.5299640861417
√158 = 12.5698050899765
√159 = 12.6095202129185
√160 = 12.6491106406735
√161 = 12.6885775404495
√162 = 12.7279220613579
√163 = 12.7671453348037
√164 = 12.8062484748657
√165 = 12.8452325786651
√166 = 12.8840987267251
√167 = 12.9228479833201
√168 = 12.9614813968157
√169 = 13
√170 = 13.0384048104053
√171 = 13.076696830622
√172 = 13.114877048604
√173 = 13.1529464379659
√174 = 13.1909059582729
√175 = 13.228756555323
√176 = 13.2664991614216
√177 = 13.3041346956501
√178 = 13.3416640641263
√179 = 13.3790881602597
√180 = 13.4164078649987
√181 = 13.4536240470737
√182 = 13.490737563232
√183 = 13.5277492584687
√184 = 13.5646599662505
√185 = 13.6014705087354
√186 = 13.6381816969859
√187 = 13.6747943311773
√188 = 13.7113092008021
√189 = 13.7477270848675
√190 = 13.7840487520902
√191 = 13.8202749610853
√192 = 13.856406460551
√193 = 13.8924439894498
√194 = 13.9283882771841
√195 = 13.9642400437689
√196 = 14
√197 = 14.0356688476182
√198 = 14.0712472794703
√199 = 14.1067359796659
√200 = 14.142135623731
√201 = 14.1774468787578
√202 = 14.2126704035519
√203 = 14.247806848775
√204 = 14.2828568570857
√205 = 14.3178210632764
√206 = 14.3527000944073
√207 = 14.3874945699382
√208 = 14.422205101856
√209 = 14.456832294801
√210 = 14.4913767461894
√211 = 14.5258390463339
√212 = 14.560219778561
√213 = 14.5945195193264
√214 = 14.6287388383278
√215 = 14.6628782986152
√216 = 14.6969384566991
√217 = 14.7309198626562
√218 = 14.7648230602334
√219 = 14.7986485869487
√220 = 14.8323969741913
√221 = 14.8660687473185
√222 = 14.8996644257513
√223 = 14.9331845230681
√224 = 14.9666295470958
√225 = 15
√226 = 15.0332963783729
√227 = 15.0665191733194
√228 = 15.0996688705415
√229 = 15.1327459504216
√230 = 15.1657508881031
√231 = 15.1986841535707
√232 = 15.2315462117278
√233 = 15.2643375224737
√234 = 15.2970585407784
√235 = 15.3297097167559
√236 = 15.3622914957372
√237 = 15.3948043183407
√238 = 15.4272486205415
√239 = 15.4596248337403
√240 = 15.4919333848297
√241 = 15.52417469626
√242 = 15.556349186104
√243 = 15.5884572681199
√244 = 15.6204993518133
√245 = 15.6524758424985
√246 = 15.6843871413581
√247 = 15.7162336455017
√248 = 15.7480157480236
√249 = 15.7797338380595
√250 = 15.8113883008419
√251 = 15.8429795177549
√252 = 15.8745078663875
√253 = 15.9059737205869
√254 = 15.9373774505092
√255 = 15.9687194226713
√256 = 16
√257 = 16.0312195418814
√258 = 16.062378404209
√259 = 16.0934769394311
√260 = 16.1245154965971
√261 = 16.1554944214035
√262 = 16.1864140562386
√263 = 16.2172747402269
√264 = 16.2480768092719
√265 = 16.2788205960997
√266 = 16.3095064303001
√267 = 16.3401346383682
√268 = 16.3707055437449
√269 = 16.4012194668567
√270 = 16.431676725155
√271 = 16.4620776331543
√272 = 16.4924225024706
√273 = 16.5227116418583
√274 = 16.5529453572468
√275 = 16.583123951777
√276 = 16.6132477258362
√277 = 16.6433169770932
√278 = 16.6733320005331
√279 = 16.7032930884901
√280 = 16.7332005306815
√281 = 16.7630546142402
√282 = 16.7928556237467
√283 = 16.8226038412607
√284 = 16.8522995463527
√285 = 16.8819430161341
√286 = 16.9115345252878
√287 = 16.9410743460974
√288 = 16.9705627484771
√289 = 17
√290 = 17.0293863659264
√291 = 17.058722109232
√292 = 17.0880074906351
√293 = 17.1172427686237
√294 = 17.1464281994822
√295 = 17.1755640373177
√296 = 17.2046505340853
√297 = 17.2336879396141
√298 = 17.2626765016321
√299 = 17.2916164657906
√300 = 17.3205080756888
√301 = 17.3493515728975
√302 = 17.3781471969828
√303 = 17.4068951855292
√304 = 17.4355957741627
√305 = 17.464249196573
√306 = 17.4928556845359
√307 = 17.5214154679352
√308 = 17.5499287747842
√309 = 17.5783958312469
√310 = 17.606816861659
√311 = 17.6351920885484
√312 = 17.6635217326557
√313 = 17.6918060129541
√314 = 17.7200451466693
√315 = 17.7482393492988
√316 = 17.7763888346312
√317 = 17.8044938147649
√318 = 17.832554500127
√319 = 17.8605710994918
√320 = 17.8885438199983
√321 = 17.9164728671689
√322 = 17.9443584449264
√323 = 17.9722007556114
√324 = 18
√325 = 18.0277563773199
√326 = 18.0554700852678
√327 = 18.0831413200251
√328 = 18.1107702762748
√329 = 18.1383571472171
√330 = 18.1659021245849
√331 = 18.1934053986603
√332 = 18.2208671582886
√333 = 18.2482875908947
√334 = 18.2756668824971
√335 = 18.3030052177231
√336 = 18.3303027798234
√337 = 18.3575597506858
√338 = 18.3847763108502
√339 = 18.411952639522
√340 = 18.4390889145858
√341 = 18.4661853126194
√342 = 18.4932420089069
√343 = 18.5202591774521
√344 = 18.5472369909914
√345 = 18.5741756210067
√346 = 18.6010752377383
√347 = 18.6279360101972
√348 = 18.6547581061776
√349 = 18.6815416922694
√350 = 18.7082869338697
√351 = 18.7349939951952
√352 = 18.7616630392937
√353 = 18.7882942280559
√354 = 18.8148877222268
√355 = 18.8414436814168
√356 = 18.8679622641132
√357 = 18.8944436276912
√358 = 18.9208879284245
√359 = 18.9472953214964
√360 = 18.9736659610103
√361 = 19
√362 = 19.0262975904404
√363 = 19.0525588832577
√364 = 19.0787840283389
√365 = 19.1049731745428
√366 = 19.131126469709
√367 = 19.157244060668
√368 = 19.1833260932509
√369 = 19.2093727122985
√370 = 19.2353840616713
√371 = 19.2613602842582
√372 = 19.2873015219859
√373 = 19.313207915828
√374 = 19.3390796058137
√375 = 19.3649167310371
√376 = 19.3907194296653
√377 = 19.4164878389476
√378 = 19.4422220952236
√379 = 19.4679223339318
√380 = 19.4935886896179
√381 = 19.5192212959431
√382 = 19.5448202856921
√383 = 19.5703857907809
√384 = 19.5959179422654
√385 = 19.6214168703486
√386 = 19.6468827043885
√387 = 19.672315572906
√388 = 19.6977156035922
√389 = 19.723082923316
√390 = 19.7484176581315
√391 = 19.7737199332852
√392 = 19.7989898732233
√393 = 19.824227601599
√394 = 19.8494332412792
√395 = 19.8746069143518
√396 = 19.8997487421324
√397 = 19.9248588451713
√398 = 19.94993734326
√399 = 19.9749843554382
√400 = 20
√401 = 20.0249843945008
√402 = 20.0499376557634
√403 = 20.0748598998847
√404 = 20.0997512422418
√405 = 20.1246117974981
√406 = 20.1494416796099
√407 = 20.174241001832
√408 = 20.1990098767242
√409 = 20.2237484161567
√410 = 20.2484567313166
√411 = 20.2731349327133
√412 = 20.2977831301844
√413 = 20.3224014329016
√414 = 20.3469899493758
√415 = 20.3715487874634
√416 = 20.3960780543711
√417 = 20.4205778566621
√418 = 20.4450483002609
√419 = 20.4694894904587
√420 = 20.4939015319192
√421 = 20.5182845286832
√422 = 20.5426385841741
√423 = 20.5669638012031
√424 = 20.591260281974
√425 = 20.6155281280883
√426 = 20.6397674405503
√427 = 20.6639783197718
√428 = 20.6881608655772
√429 = 20.712315177208
√430 = 20.7364413533277
√431 = 20.7605394920267
√432 = 20.7846096908265
√433 = 20.8086520466848
√434 = 20.8326666559997
√435 = 20.8566536146142
√436 = 20.8806130178211
√437 = 20.9045449603669
√438 = 20.9284495364563
√439 = 20.952326839757
√440 = 20.976176963403
√441 = 21
√442 = 21.0237960416286
√443 = 21.0475651798492
√444 = 21.0713075057055
√445 = 21.095023109729
√446 = 21.1187120819429
√447 = 21.142374511866
√448 = 21.1660104885167
√449 = 21.1896201004171
√450 = 21.2132034355964
√451 = 21.2367605815953
√452 = 21.2602916254693
√453 = 21.2837966537928
√454 = 21.3072757526625
√455 = 21.3307290077015
√456 = 21.3541565040626
√457 = 21.3775583264319
√458 = 21.4009345590327
√459 = 21.4242852856286
√460 = 21.4476105895272
√461 = 21.4709105535839
√462 = 21.4941852602047
√463 = 21.51743479135
√464 = 21.540659228538
√465 = 21.5638586528478
√466 = 21.5870331449229
√467 = 21.6101827849743
√468 = 21.6333076527839
√469 = 21.6564078277077
√470 = 21.6794833886788
√471 = 21.7025344142107
√472 = 21.7255609824004
√473 = 21.7485631709315
√474 = 21.7715410570772
√475 = 21.7944947177034
√476 = 21.8174242292714
√477 = 21.8403296678416
√478 = 21.8632111090754
√479 = 21.8860686282393
√480 = 21.9089023002066
√481 = 21.9317121994613
√482 = 21.9544984001002
√483 = 21.9772609758359
√484 = 22
√485 = 22.0227155455452
√486 = 22.0454076850486
√487 = 22.0680764907139
√488 = 22.0907220343745
√489 = 22.113344387496
√490 = 22.1359436211787
√491 = 22.1585198061603
√492 = 22.1810730128188
√493 = 22.2036033111745
√494 = 22.2261107708929
√495 = 22.248595461287
√496 = 22.2710574513201
√497 = 22.293496809608
√498 = 22.3159136044214
√499 = 22.3383079036887
√500 = 22.3606797749979
立方根
3√0 = 0
3√1 = 1
3√2 = 1.25992104989487
3√3 = 1.44224957030741
3√4 = 1.5874010519682
3√5 = 1.7099759466767
3√6 = 1.81712059283214
3√7 = 1.91293118277239
3√8 = 2
3√9 = 2.0800838230519
3√10 = 2.15443469003188
3√11 = 2.22398009056932
3√12 = 2.28942848510666
3√13 = 2.35133468772076
3√14 = 2.41014226417523
3√15 = 2.46621207433047
3√16 = 2.51984209978975
3√17 = 2.57128159065824
3√18 = 2.6207413942089
3√19 = 2.66840164872194
3√20 = 2.71441761659491
3√21 = 2.75892417638112
3√22 = 2.80203933065539
3√23 = 2.84386697985157
3√24 = 2.88449914061482
3√25 = 2.92401773821287
3√26 = 2.96249606840737
3√27 = 3
3√28 = 3.03658897187566
3√29 = 3.07231682568585
3√30 = 3.10723250595386
3√31 = 3.14138065239139
3√32 = 3.1748021039364
3√33 = 3.20753432999583
3√34 = 3.23961180127748
3√35 = 3.27106631018859
3√36 = 3.30192724889463
3√37 = 3.33222185164595
3√38 = 3.36197540679896
3√39 = 3.39121144301417
3√40 = 3.41995189335339
3√41 = 3.44821724038273
3√42 = 3.47602664488645
3√43 = 3.50339806038672
3√44 = 3.53034833532606
3√45 = 3.55689330449006
3√46 = 3.58304787101595
3√47 = 3.60882608013869
3√48 = 3.63424118566428
3√49 = 3.65930571002297
3√50 = 3.68403149864039
3√51 = 3.70842976926619
3√52 = 3.73251115681725
3√53 = 3.75628575422107
3√54 = 3.77976314968462
3√55 = 3.80295246076139
3√56 = 3.82586236554478
3√57 = 3.8485011312768
3√58 = 3.8708766406278
3√59 = 3.89299641587326
3√60 = 3.91486764116886
3√61 = 3.93649718310217
3√62 = 3.95789160968041
3√63 = 3.97905720789639
3√64 = 4
3√65 = 4.02072575858906
3√66 = 4.04124002062219
3√67 = 4.06154810044568
3√68 = 4.08165510191735
3√69 = 4.10156592970235
3√70 = 4.12128529980856
3√71 = 4.14081774942285
3√72 = 4.16016764610381
3√73 = 4.17933919638123
3√74 = 4.19833645380841
3√75 = 4.21716332650875
3√76 = 4.23582358425489
3√77 = 4.25432086511501
3√78 = 4.27265868169792
3√79 = 4.29084042702621
3√80 = 4.30886938006377
3√81 = 4.32674871092222
3√82 = 4.34448148576861
3√83 = 4.36207067145484
3√84 = 4.37951913988789
3√85 = 4.39682967215818
3√86 = 4.4140049624421
3√87 = 4.43104762169363
3√88 = 4.44796018113863
3√89 = 4.46474509558454
3√90 = 4.48140474655716
3√91 = 4.49794144527541
3√92 = 4.514357435474
3√93 = 4.53065489608349
3√94 = 4.54683594377634
3√95 = 4.56290263538697
3√96 = 4.57885697021333
3√97 = 4.59470089220704
3√98 = 4.61043629205845
3√99 = 4.62606500918274
3√100 = 4.64158883361278
3√101 = 4.65700950780383
3√102 = 4.67232872835526
3√103 = 4.6875481476536
3√104 = 4.70266937544151
3√105 = 4.7176939803
3√106 = 4.73262349116337
3√107 = 4.7474593985234
3√108 = 4.7622031559046
3√109 = 4.77685618103502
3√110 = 4.79141985706278
3√111 = 4.80589553370533
3√112 = 4.82028452835046
3√113 = 4.83458812711164
3√114 = 4.84880758583988
3√115 = 4.86294413109428
3√116 = 4.87699896107331
3√117 = 4.89097324650875
3√118 = 4.90486813152402
3√119 = 4.91868473445873
3√120 = 4.93242414866094
3√121 = 4.9460874432487
3√122 = 4.9596756638423
3√123 = 4.97318983326859
3√124 = 4.98663095223865
3√125 = 5
3√126 = 5.01329793496458
3√127 = 5.02652569531348
3√128 = 5.03968419957949
3√129 = 5.05277434720856
3√130 = 5.06579701910089
3√131 = 5.0787530781327
3√132 = 5.09164336965949
3√133 = 5.10446872200146
3√134 = 5.11722994691205
3√135 = 5.12992784003009
3√136 = 5.14256318131647
3√137 = 5.15513673547577
3√138 = 5.16764925236362
3√139 = 5.18010146738029
3√140 = 5.1924941018511
3√141 = 5.2048278633942
3√142 = 5.21710344627617
3√143 = 5.22932153175598
3√144 = 5.24148278841779
3√145 = 5.2535878724929
3√146 = 5.26563742817144
3√147 = 5.27763208790408
3√148 = 5.28957247269421
3√149 = 5.3014591923809
3√150 = 5.31329284591305
3√151 = 5.32507402161499
3√152 = 5.33680329744389
3√153 = 5.34848124123936
3√154 = 5.36010841096536
3√155 = 5.37168535494483
3√156 = 5.38321261208728
3√157 = 5.39469071210959
3√158 = 5.40612017575022
3√159 = 5.41750151497718
3√160 = 5.42883523318981
3√161 = 5.4401218254148
3√162 = 5.45136177849642
3√163 = 5.4625555712814
3√164 = 5.47370367479843
3√165 = 5.48480655243262
3√166 = 5.49586466009501
3√167 = 5.50687844638735
3√168 = 5.51784835276224
3√169 = 5.52877481367887
3√170 = 5.53965825675446
3√171 = 5.55049910291155
3√172 = 5.56129776652124
3√173 = 5.57205465554262
3√174 = 5.58277017165842
3√175 = 5.59344471040698
3√176 = 5.60407866131077
3√177 = 5.61467240800149
3√178 = 5.62522632834186
3√179 = 5.63574079454424
3√180 = 5.64621617328617
3√181 = 5.65665282582291
3√182 = 5.66705110809706
3√183 = 5.67741137084543
3√184 = 5.68773395970313
3√185 = 5.69801921530506
3√186 = 5.70826747338486
3√187 = 5.71847906487132
3√188 = 5.72865431598244
3√189 = 5.73879354831717
3√190 = 5.74889707894483
3√191 = 5.7589652204924
3√192 = 5.76899828122963
3√193 = 5.77899656515213
3√194 = 5.7889603720624
3√195 = 5.798889997649
3√196 = 5.8087857335637
3√197 = 5.81864786749696
3√198 = 5.82847668325146
3√199 = 5.838272460814
3√200 = 5.84803547642573
⑸ 1到20的平方根怎樣用口訣記住
1到20的平方根的口訣如下
平方根口訣：負數方根不能行，零取方根仍為零。正數方根有兩個，符號相反值相同。2作根指可省略，其它務必要寫明。負森族數只有奇次根，算術方根零或正。
1到20的平方根：1²=1 ，2²=4，3²=9，4²=16，5²=25，6²=36，7²=49，8²=64，9²=81，10²=100，11²=121，12²=144，13²=169，14²=196，15²=225 ，16²=256，17²=289，18²=324，19²=361，20²=400。
平方根口訣：11-19的平方：原數加尾數，尾平方；逢10進位；41-49的平方：尾加15，10減尾再平方，佔2位；51-59的平方：尾加二十五，尾平方佔2位；91-99的平方：尾數乘2加80，10減尾數再平方，佔2位。
(5)809的平方根等於多少擴展閱讀：
一個正數如果有平方根，那麼必定有森租兩個，它們互為相反數。顯然，如果知道了這兩個平方根的一個，那麼就可以及時的根據相反數的概念得到它的另一此春弊個平方根。
負數在實數系內不能開平方。只有在復數系內，負數才可以開平方。負數的平方根為一對共軛純虛數。例如：-1的平方根為±i，-9的平方根為±3i，其中i為虛數單位。
⑹ 平方根，算數平方根的計算公式
開平方公式：
x（n
+
1）
=
xn
+
(a
/
xn
−
xn)1
/
2.。（n，n+1是下角標）
舉例
例如，a=5：
5介於2的平方至3的平方;之間。我們取初始值2.1，2.2，2.3，2.4，2.5，2.6，2.7，2.8，2.9都可以，我們最好取
中間值2.5。
第一步：2.5+（5/2.5-2.5)1/2=2.2；
即5/2.5=2，2-2.5=-0.5，-0.5×1/2=-0.25，2.5+(-0.25)=2.25，取2位數2.2。
第二步：2.2+(5/2.2-2.2)1/2=2.23；
即5/2.2=2.27272，2.27272-2.2=-0.07272，-0.07272×1/2=-0.03636，2.2+0.03636=2.23。取3位數。
第三步：2.23+(5/2.23-2.23)1/2=2.236。
即5/2.23=2.2421525，,2.2421525-2.23=0.0121525，0.0121525×1/2=0.00607，2.23+0.00607=2.236.
每一步多取一位數。這個方法又叫反饋開方，即使你輸入一個錯誤的數值，也沒有關系，輸出值會自動調節，接近准確值。
例如a=200.
200介如10的平方---20的平方之間。初始值可以取11，12，13，14，15，16，17，18，19。我們去15.
第一步：15+（200/15-15)1/2=14。取19也一樣得出14.。：19+（200/19-19)1/2=14.。
第二步：14+(200/14-14)1/2=14.1。
第三步：14.1+（200/14.1-14.1)1/2=14.14.
抄自網路
其實手動開方很麻煩
一般是知道幾個常見數的開方即可
用計算器最簡便...
⑺ 數學根號1到根號100的平方根是多少
√1 = 1
√2 = 1.41421
√3 = 1.73205
√4 = 2
√5 = 2.23607
√6 = 2.44949
√7 = 2.64575
√8 = 2.82843
√9 = 3
√10 = 3.16228
√11 = 3.31662
√12 = 3.4641
√13 = 3.60555
√14 = 3.74166
√15 = 3.87298
√16 = 4
√17 = 4.12311
√18 = 4.24264
√19 = 4.3589
√20 = 4.47214
√21 = 4.58258
√22 = 4.69042
√23 = 4.79583
√24 = 4.89898
√25 = 5
√26 = 5.09902
√27 = 5.19615
√坦散28 = 5.2915
√29 = 5.38516
√30 = 5.47723
√31 = 5.56776
√32 = 5.65685
√33 = 5.74456
√34 = 5.83095
√35 = 5.91608
√36 = 6
√37 = 6.08276
√38 = 6.16441
√39 = 6.245
√40 = 6.32456
√41 = 6.40312
√讓洞氏42 = 6.48074
√43 = 6.55744
√44 = 6.63325
√45 = 6.7082
√46 = 6.78233
√顫瞎47 = 6.85565
√48 = 6.9282
√49 = 7
√50 = 7.07107
√51 = 7.14143
√52 = 7.2111
√53 = 7.28011
√54 = 7.34847
√55 = 7.4162
√56 = 7.48331
√57 = 7.54983
√58 = 7.61577
√59 = 7.68115
√60 = 7.74597
√61 = 7.81025
√62 = 7.87401
√63 = 7.93725
√64 = 8
√65 = 8.06226
√66 = 8.12404
√67 = 8.18535
√68 = 8.24621
√69 = 8.30662
√70 = 8.3666
√71 = 8.42615
√72 = 8.48528
√73 = 8.544
√74 = 8.60233
√75 = 8.66025
√76 = 8.7178
√77 = 8.77496
√78 = 8.83176
√79 = 8.88819
√80 = 8.94427
√81 = 9
√82 = 9.05539
√83 = 9.11043
√84 = 9.16515
√85 = 9.21954
√86 = 9.27362
√87 = 9.32738
√88 = 9.38083
√89 = 9.43398
√90 = 9.48683
√91 = 9.53939
√92 = 9.59166
√93 = 9.64365
√94 = 9.69536
√95 = 9.74679
√96 = 9.79796
√97 = 9.84886
√98 = 9.89949
√99 = 9.94987
√100 = 10
⑻ 算術平方根表
除了幾個特殊如√2=1.414、枝悄√3=1.732、√5=2.236還有記憶的必要，其他無任何任何意義。
√0 = 0
√1 = 1
√2 = 1.4142135623731
√3 = 1.73205080756888
√4 = 2
√5 = 2.23606797749979
√6 = 2.44948974278318
√7 = 2.64575131106459
√8 = 2.82842712474619
√9 = 3
√10 = 3.16227766016838
√11 = 3.3166247903554
√12 = 3.46410161513775
√13 = 3.60555127546399
√14 = 3.74165738677394
√15 = 3.87298334620742
√16 = 4
√17 = 4.12310562561766
√18 = 4.24264068711928
√19 = 4.35889894354067
√20 = 4.47213595499958
√21 = 4.58257569495584
√22 = 4.69041575982343
√23 = 4.79583152331272
√24 = 4.89897948556636
√25 = 5
√26 = 5.09901951359278
√27 = 5.19615242270663
√28 = 5.29150262212918
√29 = 5.3851648071345
√30 = 5.47722557505166
√31 = 5.56776436283002
√32 = 5.65685424949238
√33 = 5.74456264653803
√34 = 5.8309518948453
√35 = 5.91607978309962
√36 = 6
√37 = 6.08276253029822
√38 = 6.16441400296898
√39 = 6.2449979983984
√40 = 6.32455532033676
√41 = 6.40312423743285
√42 = 6.48074069840786
√43 = 6.557438524302
√碰則44 = 6.6332495807108
√45 = 6.70820393249937
√46 = 6.78232998312527
√47 = 6.85565460040104
√48 = 6.92820323027551
√49 = 7
√50 = 7.07106781186548
√51 = 7.14142842854285
√52 = 7.21110255092798
√笑搭棚53 = 7.28010988928052
√54 = 7.34846922834953
√55 = 7.41619848709566
√56 = 7.48331477354788
√57 = 7.54983443527075
√58 = 7.61577310586391
√59 = 7.68114574786861
√60 = 7.74596669241483
√61 = 7.81024967590665
√62 = 7.87400787401181
√63 = 7.93725393319377
√64 = 8
√65 = 8.06225774829855
√66 = 8.12403840463596
√67 = 8.18535277187245
√68 = 8.24621125123532
√69 = 8.30662386291807
√70 = 8.36660026534076
√71 = 8.42614977317636
√72 = 8.48528137423857
√73 = 8.54400374531753
√74 = 8.60232526704263
√75 = 8.66025403784439
√76 = 8.71779788708135
√77 = 8.77496438739212
√78 = 8.83176086632785
√79 = 8.88819441731559
√80 = 8.94427190999916
√81 = 9
√82 = 9.05538513813742
√83 = 9.1104335791443
√84 = 9.16515138991168
√85 = 9.21954445729289
√86 = 9.2736184954957
√87 = 9.32737905308882
√88 = 9.38083151964686
√89 = 9.4339811320566
√90 = 9.48683298050514
√91 = 9.53939201416946
√92 = 9.59166304662544
√93 = 9.64365076099295
√94 = 9.69535971483266
√95 = 9.74679434480896
√96 = 9.79795897113271
√97 = 9.8488578017961
√98 = 9.89949493661167
√99 = 9.9498743710662
√100 = 10
√101 = 10.0498756211209
√102 = 10.0995049383621
√103 = 10.1488915650922
√104 = 10.1980390271856
√105 = 10.2469507659596
√106 = 10.295630140987
√107 = 10.3440804327886
√108 = 10.3923048454133
√109 = 10.4403065089106
√110 = 10.4880884817015
√111 = 10.5356537528527
√112 = 10.5830052442584
√113 = 10.6301458127347
√114 = 10.6770782520313
√115 = 10.7238052947636
√116 = 10.770329614269
√117 = 10.816653826392
√118 = 10.8627804912002
√119 = 10.9087121146357
√120 = 10.9544511501033
√121 = 11
√122 = 11.0453610171873
√123 = 11.0905365064094
√124 = 11.13552872566
√125 = 11.1803398874989
√126 = 11.2249721603218
√127 = 11.2694276695846
√128 = 11.3137084989848
√129 = 11.3578166916005
√130 = 11.4017542509914
√131 = 11.4455231422596
√132 = 11.4891252930761
√133 = 11.5325625946708
√134 = 11.5758369027902
√135 = 11.6189500386223
√136 = 11.6619037896906
√137 = 11.7046999107196
√138 = 11.7473401244707
√139 = 11.7898261225516
√140 = 11.8321595661992
√141 = 11.8743420870379
√142 = 11.916375287813
√143 = 11.9582607431014
√144 = 12
√145 = 12.0415945787923
√146 = 12.0830459735946
√147 = 12.1243556529821
√148 = 12.1655250605964
√149 = 12.2065556157337
√150 = 12.2474487139159
√151 = 12.2882057274445
√152 = 12.328828005938
√153 = 12.369316876853
√154 = 12.4096736459909
√155 = 12.4498995979887
√156 = 12.4899959967968
√157 = 12.5299640861417
√158 = 12.5698050899765
√159 = 12.6095202129185
√160 = 12.6491106406735
√161 = 12.6885775404495
√162 = 12.7279220613579
√163 = 12.7671453348037
√164 = 12.8062484748657
√165 = 12.8452325786651
√166 = 12.8840987267251
√167 = 12.9228479833201
√168 = 12.9614813968157
√169 = 13
√170 = 13.0384048104053
√171 = 13.076696830622
√172 = 13.114877048604
√173 = 13.1529464379659
√174 = 13.1909059582729
√175 = 13.228756555323
√176 = 13.2664991614216
√177 = 13.3041346956501
√178 = 13.3416640641263
√179 = 13.3790881602597
√180 = 13.4164078649987
√181 = 13.4536240470737
√182 = 13.490737563232
√183 = 13.5277492584687
√184 = 13.5646599662505
√185 = 13.6014705087354
√186 = 13.6381816969859
√187 = 13.6747943311773
√188 = 13.7113092008021
√189 = 13.7477270848675
√190 = 13.7840487520902
√191 = 13.8202749610853
√192 = 13.856406460551
√193 = 13.8924439894498
√194 = 13.9283882771841
√195 = 13.9642400437689
√196 = 14
√197 = 14.0356688476182
√198 = 14.0712472794703
√199 = 14.1067359796659
√200 = 14.142135623731
√201 = 14.1774468787578
√202 = 14.2126704035519
√203 = 14.247806848775
√204 = 14.2828568570857
√205 = 14.3178210632764
√206 = 14.3527000944073
√207 = 14.3874945699382
√208 = 14.422205101856
√209 = 14.456832294801
√210 = 14.4913767461894
√211 = 14.5258390463339
√212 = 14.560219778561
√213 = 14.5945195193264
√214 = 14.6287388383278
√215 = 14.6628782986152
√216 = 14.6969384566991
√217 = 14.7309198626562
√218 = 14.7648230602334
√219 = 14.7986485869487
√220 = 14.8323969741913
√221 = 14.8660687473185
√222 = 14.8996644257513
√223 = 14.9331845230681
√224 = 14.9666295470958
√225 = 15
√226 = 15.0332963783729
√227 = 15.0665191733194
√228 = 15.0996688705415
√229 = 15.1327459504216
√230 = 15.1657508881031
√231 = 15.1986841535707
√232 = 15.2315462117278
√233 = 15.2643375224737
√234 = 15.2970585407784
√235 = 15.3297097167559
√236 = 15.3622914957372
√237 = 15.3948043183407
√238 = 15.4272486205415
√239 = 15.4596248337403
√240 = 15.4919333848297
√241 = 15.52417469626
√242 = 15.556349186104
√243 = 15.5884572681199
√244 = 15.6204993518133
√245 = 15.6524758424985
√246 = 15.6843871413581
√247 = 15.7162336455017
√248 = 15.7480157480236
√249 = 15.7797338380595
√250 = 15.8113883008419
√251 = 15.8429795177549
√252 = 15.8745078663875
√253 = 15.9059737205869
√254 = 15.9373774505092
√255 = 15.9687194226713
√256 = 16
√257 = 16.0312195418814
√258 = 16.062378404209
√259 = 16.0934769394311
√260 = 16.1245154965971
√261 = 16.1554944214035
√262 = 16.1864140562386
√263 = 16.2172747402269
√264 = 16.2480768092719
√265 = 16.2788205960997
√266 = 16.3095064303001
√267 = 16.3401346383682
√268 = 16.3707055437449
√269 = 16.4012194668567
√270 = 16.431676725155
√271 = 16.4620776331543
√272 = 16.4924225024706
√273 = 16.5227116418583
√274 = 16.5529453572468
√275 = 16.583123951777
√276 = 16.6132477258362
√277 = 16.6433169770932
√278 = 16.6733320005331
√279 = 16.7032930884901
√280 = 16.7332005306815
√281 = 16.7630546142402
√282 = 16.7928556237467
√283 = 16.8226038412607
√284 = 16.8522995463527
√285 = 16.8819430161341
√286 = 16.9115345252878
√287 = 16.9410743460974
√288 = 16.9705627484771
√289 = 17
√290 = 17.0293863659264
√291 = 17.058722109232
√292 = 17.0880074906351
√293 = 17.1172427686237
√294 = 17.1464281994822
√295 = 17.1755640373177
√296 = 17.2046505340853
√297 = 17.2336879396141
√298 = 17.2626765016321
√299 = 17.2916164657906
√300 = 17.3205080756888
√301 = 17.3493515728975
√302 = 17.3781471969828
√303 = 17.4068951855292
√304 = 17.4355957741627
√305 = 17.464249196573
√306 = 17.4928556845359
√307 = 17.5214154679352
√308 = 17.5499287747842
√309 = 17.5783958312469
√310 = 17.606816861659
√311 = 17.6351920885484
√312 = 17.6635217326557
√313 = 17.6918060129541
√314 = 17.7200451466693
√315 = 17.7482393492988
√316 = 17.7763888346312
√317 = 17.8044938147649
√318 = 17.832554500127
√319 = 17.8605710994918
√320 = 17.8885438199983
√321 = 17.9164728671689
√322 = 17.9443584449264
√323 = 17.9722007556114
√324 = 18
√325 = 18.0277563773199
√326 = 18.0554700852678
√327 = 18.0831413200251
√328 = 18.1107702762748
√329 = 18.1383571472171
√330 = 18.1659021245849
√331 = 18.1934053986603
√332 = 18.2208671582886
√333 = 18.2482875908947
√334 = 18.2756668824971
√335 = 18.3030052177231
√336 = 18.3303027798234
√337 = 18.3575597506858
√338 = 18.3847763108502
√339 = 18.411952639522
√340 = 18.4390889145858
√341 = 18.4661853126194
√342 = 18.4932420089069
√343 = 18.5202591774521
√344 = 18.5472369909914
√345 = 18.5741756210067
√346 = 18.6010752377383
√347 = 18.6279360101972
√348 = 18.6547581061776
√349 = 18.6815416922694
√350 = 18.7082869338697
√351 = 18.7349939951952
√352 = 18.7616630392937
√353 = 18.7882942280559
√354 = 18.8148877222268
√355 = 18.8414436814168
√356 = 18.8679622641132
√357 = 18.8944436276912
√358 = 18.9208879284245
√359 = 18.9472953214964
√360 = 18.9736659610103
√361 = 19
√362 = 19.0262975904404
√363 = 19.0525588832577
√364 = 19.0787840283389
√365 = 19.1049731745428
√366 = 19.131126469709
√367 = 19.157244060668
√368 = 19.1833260932509
√369 = 19.2093727122985
√370 = 19.2353840616713
√371 = 19.2613602842582
√372 = 19.2873015219859
√373 = 19.313207915828
√374 = 19.3390796058137
√375 = 19.3649167310371
√376 = 19.3907194296653
√377 = 19.4164878389476
√378 = 19.4422220952236
√379 = 19.4679223339318
√380 = 19.4935886896179
√381 = 19.5192212959431
√382 = 19.5448202856921
√383 = 19.5703857907809
√384 = 19.5959179422654
√385 = 19.6214168703486
√386 = 19.6468827043885
√387 = 19.672315572906
√388 = 19.6977156035922
√389 = 19.723082923316
√390 = 19.7484176581315
√391 = 19.7737199332852
√392 = 19.7989898732233
√393 = 19.824227601599
√394 = 19.8494332412792
√395 = 19.8746069143518
√396 = 19.8997487421324
√397 = 19.9248588451713
√398 = 19.94993734326
√399 = 19.9749843554382
√400 = 20
√401 = 20.0249843945008
√402 = 20.0499376557634
√403 = 20.0748598998847
√404 = 20.0997512422418
√405 = 20.1246117974981
√406 = 20.1494416796099
√407 = 20.174241001832
√408 = 20.1990098767242
√409 = 20.2237484161567
√410 = 20.2484567313166
√411 = 20.2731349327133
√412 = 20.2977831301844
√413 = 20.3224014329016
√414 = 20.3469899493758
√415 = 20.3715487874634
√416 = 20.3960780543711
√417 = 20.4205778566621
√418 = 20.4450483002609
√419 = 20.4694894904587
√420 = 20.4939015319192
√421 = 20.5182845286832
√422 = 20.5426385841741
√423 = 20.5669638012031
⑼ 80是多少的平方
即求80的平方根，准確值為±√80即±4√5，所以80是±4√5的平方，近似為±8.94的平方。
因為9*9=81，所以80應該是8.9左右的一個實數的平方，但鑒於80並不是個完全平方數，所以√80=4√陪敬5，並不是個整數，甚至不是個有理數。
乘法的計演算法則：
數位對齊，從右邊起，依次用第二個因數每位上的數去乘第一個因數，乘到哪一位，得數的末尾就和第二個因數的哪一位對齊。
凡是被乘數遇到989697等大數聯運算時，期法為：被乘數後位按10補加補數，前位遇到9不動，前位遇到6、7、8時，按9補加補數次數（均臘猜由下位補加補數次數），最後被乘數首位減補數一次。
例如：9798x8679=85036842（8679的補數1321）算序：被乘數個位8的下位加2642，得979-82642。被乘數十位9不動。被乘數百位7的下位加2642，得9-8246842。被乘數的首位減1321，得85036842（乘輪亂型積）。
⑽ 怎樣求1到100的算術平方根
1、一般地說，若一個非負數x的平方等於a，即x²=a，則這個數x叫做a的算術平方根。
2、舉例來說：9的平方早汪根為±3 ；9的算術平方根為3，正數的平方根都是前面加±，算術平方根全部都是非負數（0也在內，0的算數平方根為0）。
3、對於本題來說，1-100的算數平方根計算如下：
√1 = 1
√2 = 1.41421
√3 = 1.73205
√4 = 2
√5 = 2.23607
√6 = 2.44949
√7 = 2.64575
√8 = 2.82843
√9 = 3
√10 = 3.16228
√11 = 3.31662
√12 = 3.4641
√13 = 3.60555
√14 = 3.74166
√15 = 3.87298
√16 = 4
√17 = 4.12311
√18 = 4.24264
√19 = 4.3589
√20 = 4.47214
√21 = 4.58258
√22 = 4.69042
√23 = 4.79583
√24 = 4.89898
√25 = 5
√26 = 5.09902
√27 = 5.19615
√28 = 5.2915
√29 = 5.38516
√30 = 5.47723
√31 = 5.56776
√32 = 5.65685
√33 = 5.74456
√34 = 5.83095
√35 = 5.91608
√36 = 6
√37 = 6.08276
√38 = 6.16441
√39 = 6.245
√40 = 6.32456
√41 = 6.40312
√42 = 6.48074
√43 = 6.55744
√44 = 6.63325
√45 = 6.7082
√46 = 6.78233
√47 = 6.85565
√48 = 6.9282
√49 = 7
√50 = 7.07107
√51 = 7.14143
√52 = 7.2111
√53 = 7.28011
√54 = 7.34847
√55 = 7.4162
√56 = 7.48331
√57 = 7.54983
√58 = 7.61577
√59 = 7.68115
√60 = 7.74597
√61 = 7.81025
√62 = 7.87401
√63 = 7.93725
√64 = 8
√65 = 8.06226
√66 = 8.12404
√67 = 8.18535
√68 = 8.24621
√69 = 8.30662
√70 = 8.3666
√71 = 8.42615
√72 = 8.48528
√73 = 8.544
√74 = 8.60233
√75 = 8.66025
√76 = 8.7178
√77 = 8.77496
√78 = 8.83176
√79 = 8.88819
√80 = 8.94427
√81 = 9
√82 = 9.05539
√83 = 9.11043
√84 = 9.16515
√85 = 9.21954
√86 = 9.27362
√87 = 9.32738
√88 = 9.38083
√89 = 9.43398
√90 = 9.48683
√91 = 9.53939
√92 = 9.59166
√93 = 9.64365
√94 = 9.69536
√95 = 9.74679
√96 = 9.79796
√97 = 9.84886
√98 = 9.89949
√99 = 9.94987
√100 = 10
擴展：
平方根與算術平方根的區別：
1、平方根的定義：若x²=a,則x為a 的平方根，若2²=4,2是4的平方根,（-2）²=4,-2是4的平方根。
2、算術平方根的定義：一個非負數的正的平方根叫做它的算術平方根，陸返仔如：2和-2都是4的平方根,而2是4的算術平方根。
3、個數不同：正數的平方根有兩個且互為相反數，正數的算術平方根只有一個。
4、表示方法不同：前者非負數a的平方根為a的正負平方根，後者非負數a的算術平方根為a的世納正的平方根。