GRE數(shù)學備考（二）18主講人：Celine算術部分的基本問題1.正整數(shù)n有奇數(shù)個因子，則n為完全平方數(shù)

2.因子個數(shù)求解公式：將整數(shù)n分解為質因子乘積形式,然后將每個質因子的冪分別加一相乘.n=a*a*a*b*b*c則因子個數(shù)=(3+1)(2+1)(1+1)eg.200=2*2*2*5*5因子個數(shù)=(3+1)(2+1)=12個3.能被8整除的數(shù)，后三位的和能被8整除能被9整除的數(shù)，各位數(shù)的和能被9整除.能被3整除的數(shù)，各位數(shù)的和能被3整除.計算的基本知識整數(shù)Whenintegersaremultiplied,eachofthemultipliedintegersiscalledafactorordivisoroftheresultingproduct.Forexample,so2,3,and10are(2)(3)(10)=60,factorsof60.Theleastcommonmultipleoftwononzerointegersaandbistheleastpositiveintegerthatisamultipleofbothaandb.Forexample,theleastcommonmultipleof30and75is150.Thegreatestcommondivisor(orgreatestcommonfactor)oftwononzerointegersaandbisthegreatestpositiveintegerthatisadivisorofbothaandb.d15,andthegreatestoftheseis15.Whenanintegeraisdividedbyanintegerb,wherebisadivisorofa,theresultisalwaysadivisorofa.Forexample,when60isdividedby6(oneofitsdivisors),theresultis10,whichisanotherdivisorof60.Aprimenumberisanintegergreaterthan1thathasonlytwopositivedivisors:1anditself.The?rsttenprimenumbersare2,3,5,7,11,13,17,19,23,and29.primedivisors.Suchanexpressioniscalledaprimefactorization.Hereareseveralexamplesofprimefactorizations.212=(2)(2)(3)=(2)(3)14=(2)(7)481=(3)(3)(3)(3)=32338=(2)(13)(13)=(2)(13)52800=(2)(2)(2)(2)(2)(5)(5)=(2)(5)1,155=(3)(5)(7)(11)Anintegergreaterthan1thatisnotaprimenumberiscalledacompositenumber.The?rsttencompositenumbersare4,6,8,9,10,12,14,15,16,and18.

1/10/2023指數(shù)1/10/20231/10/2023真題演示擔任講師的好處真題演示擔任講師的好處真題演示擔任講師的好處真題演示異展－進入正題，展開培訓道具用1/10/2023121/10/2023真題演示擔任講師的好處真題演示擔任講師的好處真題演示真題演示1/10/2023真題演示成人喜歡的課堂氣氛真題演示擔任講師的好處真題演示擔任講師的好處真題演示異展－進入正題，展開培訓道具用1/10/20231/10/2023真題演示真題演示1/10/20231/10/20231/10/2023真題演示講師的角色概述成人的學習特點授課的過程及技巧異常情況的處理正文展－進入正題，展開培訓表達技巧講師的角色概述成人的學習特點授課的過程及技巧異常情況的處理展－進入正題，展開培訓控場技巧678121234591011GRE數(shù)學考試詞匯：數(shù)學運算add，plus加subtract減difference差multiply,times乘product積divide除divisible可被整除的dividedevenly被整除divisor因子，除數(shù)q