第一章计算题训练基础篇.docx

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1、第一章计算题训练基础篇知识要点：1、熟记分数和小数百分数最简比互化中的常见数1/8=0.125,1/4=0.25,3/8=0.375,1/2=0.5,5/8=0.6253/4=0.75,7/8=0.8752掌握简便运算技巧加法交换律和结合律a+b=b+a(ab)+c=a+(b+c)乘法交换律，结合律，分配律ab=ba(ab)c=a(bc)(a+b)c=ac+bc(a-b)c=ac-bc除法分配律(a+b)c=ac+bc(a-b)c=ac-bca-b-c=a-(b+c)a-(b-c)=a-b+cabc=a(bc)3 平方差公式：(a+b)(a-b)=a2b24 熟记100以内质数:2,3,5,7

2、,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,83,89,975熟记1-20的平方1,4,9,16,25,36,49,64,81,100,121,144,169,196,225,256,289,324,361,4001-10的立方1,8,27,64,125,216,343,512,729,10002的1次方到10次方；3的1次方到8次方3,9,27,81,243,729,2187,65616掌握等差数列和=(首项+末项)X项数+2项数=(末项-首项)公差+1一用分配律凑整1719999279121022761371997999二用

3、结合律凑整2548125368375561240.125240.375799225312525三化多位数为一位数2722824.245484537814.2x45四凑整意识之分配律【例1】计算：200.9X20.08-200.8X20.07【巩固】计算:20.0931.52,009317+200.93.68=【巩固】计算:2.009x43+20.09x2.9+200.9x0.28=【巩固】计算:19993.14199.931.4+19.99314.【巩固】计算:199.919.98-199.819.97【巩固】计算:10.373.41.719.26=【例2】计算：6.258.27163.750

4、.8278【巩固】计算:20.0962+200.93.9-7x2.87=【巩固】计算:2.89x47+1.53-1.4x1.1+24x0.11+288x0.53-0.1=【巩固】计算:2237.5+22.312.5+2304-0.72.5+1=【巩固】计算：19.9837+199.82.3+9.9980【巩固】计算：3790.038+1590.00621+3.79x0.121【巩固】计算78.16x1.45+3.14x21.84+169x0.7816【巩固】计算:7.8I61.45+3.142.184+1.697.816=【巩固】计算：147.758.4+4.792+4092.1+0.9521

5、479【例3】计算：1253.6-79+833.6【例4】计算8.11.3-81.3+1.91.3+11.91.3【例5】(2)2003200111120037337【例6】计算：5L28.1+119.25+5370.19【例7计算：2237.5+22.312.5+2304-0.72.5+l【巩固】1.2517.6+360.8264125=【例8】计算：2007-(8.58,5-1.51.5)10160-03.【巩固】计算(980X65320)(66+98X64)【巩固】2004.051997.05-2001.051999.05【巩固】(873x477-198)+(476x874+199)【例

6、9】计算：1.23452+0.765522.4690.7655.第二节配对和凑整意识知识要点:哪些数需要配对？I分母相同的2能抵消的3能约分的4能凑整的5整数与整数,分数与分数6加数与加数，减数与减数模块一：分组凑整思想例191.5+88.8+90.2+270.4+89.6+186.7+91.8【巩固】2006+2006+2006+2006+994+994+994+0994=【例2】计算【例3】计算56.43+12.96+13.574.338.965.67【巩固】3.17+7.48-2.38+0.53-3.48-1.62+5.3【例4】计算1+0.99-0.98-0.970.96+0.95-0

7、.94-0.93+0.04+0.03-0.02-0.01模块二、加补凑整思想【例5同学们，你们有什么好办法又快又准的算出下面各题的答案？把你的好方法讲一讲！也当一次小老师！(1) 0.9+0.99+0.999+0.9999+0.99999(2) 1.996+19.97+199.8(3) 0.7+9.7+99.7+999999999.7【巩固】请你认真计算下面两道题看谁算得最准确(1)9.99629.98169.9+3999.5(2)89+899+8999+89999+899999模块三、位值原理例6(123456789.987654321+234567891.198765432+9123456

8、78.876543219)9【例7】124.68+324.68+524.68+724.68+924.68【巩固】325.24+425.24+625.24+925.24+525.24模块四、基准数思想【例8计算().9+0.99+0.999+0.9999+0.99999【巩固】1.996+19.97+199.8例io!+WWWKL12223333312+199519951995+19951+1995例11kfa+2+2+23420JU45AYf2+3+20)U53+一201818+192019+一20五综合训练57例1、57-JO2001-l-44巩固练习：1997x19971998601-l-

9、55彳列2、200597.75+4010l.12537llll+77779巩固练习：4.72.8+3.69.4999778+333666例3、199208-198209巩固练习：3567-34681324、-39+-25+-35551119巩固练习：17X至+llJoJO例5、123434-341212巩固练习：201820181998-19981998X2018例 6、 12312312312415731巩固练习：15731573-15741575例7、159-105535353104巩固练习:169Illlll131313+200420022003例8、1477101+100x103巩固练

10、习:13557HF7x9299x1011-5-+62_9_11_1212-20+30-42”1956-72+90例9、zl 1(-+- 8 9+w+x+m+TT+9+w+x+m+巩固练习：弓+3；+(1+；+9；)-(l+g+K+$x(；+3-)X(H11)(1)(-H11)2320102320123201232010；1317.62011.4(2011.412.5)2.45-(0.13l400)9992+19998llll+99998573+69757236361573697-124727220100.31.2I20120.520129799X49984211423+lo-+71377132

11、Q3-(7.753.3759.253-)927816.251.7+0.751.71,4l-17.6+36-+2.6412.5452009 2010)200920101227427 7 277121(19.2 + 13) 6.25 + (40.8 + 26)6-3 15 U 30 29 - + 0.375 + 38 8 37373739 空+ 148x 也+ 48 卫1491491492 5 .3 7 n 4 951-71-+ 91-3 34 45 5201120112011201210015-+ 198198- + 1131992001-328(3282.5)1.20.752.50.08575

12、-7.50.1(6-5.43+4.57-)-(1-)1.444252469456.879443.48+60l0.0357.15x2.5x18-1.25x28x7.154213”12422+lo-+915991522012)20112012331Q(15-17.7l一一0.75)104323C2K45、-73一(3I)+3.4X511171151.4Ur,八r1414/Cr15.760.21316.37191919190911.566.8+2.41.56+9.20.4467.854.312219%1095”6“11159179 9 1779+50-+76(-)+23(-+)-53(-)235353762376._161_16._6._1164.75+15F4.75+151141111411W2J2+LZ132251356313+860.25+0.62586-+0.1258