专题训练一1 专题一:典型的计算题及解题常用方法在小学计算题中有好多题型方法新颖独特,在升重点中学考试和进入中学分班考试中,多有出现,有的学生因为没见过这种题型常常得分很少或得零分,其实这种题型只要掌握一定的解题方法和规律一点都不难。下面老师跟你支支招:一、 熟记规律,常能化难为易。① 25×4=100, ②125×8=1000,③41 =0.25=25%,④43 =0.75=75%, ⑤81 =0.125=12.5%, ⑥83 =0.375=37.5%, ⑦85 =0.625=62.5%, ⑧87 =0.875=87.5% 利用① 12321=111×111,1234321=1111×1111,123454321=11111×11111 ②123123=123×1001,12341234=1234×10001 ③12345679×9=111111111 等规律巧解题:9999966666123454321 ×108 11234565432999999888888÷36 52552525225225252552552525225220102010×1999-2010×19991999 12345679×63 72×12345679 二、利用积不变、拆数和乘法分配率巧解计算题:28.67 ×67+3.2 ×286.7+573.4 ×0.05 专题训练一2 314×0.043+3.14 ×7.2-31.4 ×0.15 41.2×8.1+11 ×9.25+53.7 ×1.9 19931993×1993-19931992×1992-19931992 1.993 ×1993000+19.92 ×199200-199.3 ×19920-1992 ×1991 333×332332333-332 ×333333332 180-97679679597679648-411363362411363627-124894894123267专题训练一3 211998-20001)+219981-20001)- 2000× (19981+21) +31510512849636423212515520124159310625319999×2222+3333×3334 4444×2222+8888×8889 4561+4564563003+45645645623023023三、牢记设字母代入法专题训练一4 (1+0.21+0.32 )×( 0.21+0.32+0.43 )- (1+0.21+0.32+0.43 )×(0.21+0.32 )(1+0.23+0.34 )×( 0.23+0.34+0.65 )- (1+0.23+0.34+0.65 )×(0.23+0.34 )(1+ 21+ 31+ 41)×( 21+ 31+ 41+ 51)- (1+ 21+ 31+ 41+ 51)×( 21+ 31+ 41)( 111+ 211+ 311+ 411)×( 211+ 311+ 411+ 511)-( 111+ 211+ 311+ 411+ 511)×( 211+ 311+ 411)( 135531+ 357579+ 975753)×( 357579+ 975753+ 531135)- ( 135531+ 357579+ 975753+ 531135)×( 357579+ 975753)四、利用 a÷b= ba巧解计算题:①( 6.4 ×480×33.3 )÷( 3.2 ×120×66.6 )②(514+415)÷ (43+53)专题训练一5 五、利用裂项法巧解计算题211+321+431+ ⋯+100991311+531+751+⋯ +1191...