五上數(shù)學(xué)小數(shù)乘法簡(jiǎn)便計(jì)算典型例題9.8×1.2＋9.8×18.8＝9.8×（1.2＋18.8）＝9.8×20＝1962.5×26.8×4＝（2.5×4）×26.8＝10×26.8＝2683.26×5.7－3.26×0.7＝3.26×（5.7－0.7）＝3.26×5＝16.30.39×101＝0.39×（100＋1）＝0.39×100＋0.39×1＝39＋0.39＝39.390.25×7.05×0.4＝0.25×7.05×0.4＝0.25×0.4×7.05＝0.1×7.05＝0.7055.1×10.3＝5.1×（10＋0.3）＝5.1×10＋5.1×0.3＝51＋1.53＝52.535.7×4.8＋5.2×5.7＝5.7×（4.8＋5.2）＝5.7×10＝578×3.7×0.125＝（8×0.125）×3.7＝1×3.7＝3.70.25×9.8×40＝（0.25×40）×9.8＝10×9.8＝980.125×（6.08×80）＝0.125×6.08×80＝0.125×80×6.08＝10×6.08＝60.81.25×8.8＝1.25×（8×1.1）＝1.25×8×1.1＝10×1.1＝110.78×101＝0.78×（100＋1）＝0.78×100＋0.78＝78＋0.78＝78.78五上數(shù)學(xué)小數(shù)乘法簡(jiǎn)便計(jì)算典型例題1.25×3.2×0.8＝1.25×0.8×3.2＝1×3.2＝3.28.57×103﹣8.57×3＝8.57×（103﹣3）＝8.57×100＝85728.4×99＋28.4＝28.4×（99＋1）＝28.4×100＝28404.8×56.7＋5.67×5.2＝56.7×（4.8＋5.2）＝56.7×10＝56739.8×0.25×4＝39.8×（0.25×4）＝39.8×1＝39.87.6×15.8＋2.4×15.8＝15.8×（7.6＋2.4）＝15.8×10＝1583.6×99＝3.6×（100－1）＝3.6×100－3.6×1＝360－3.6＝356.40.65＋9.9×6.5＝0.65＋99×0.65＝（99＋1）×0.65＝100×0.65＝653.42×201＝3.42×（200＋1）＝3.42×200＋3.42×1＝684＋3.42＝687.420.25×3.3×0.4＝0.25×0.4×3.3＝0.1×3.3＝0.33（1.25－0.125）×8＝1.25×8－0.125×8＝10－1＝93.8×5.6＋4.4×3.8＝3.8×（5.6＋4.4）＝3.8×10＝38五上數(shù)學(xué)小數(shù)乘法簡(jiǎn)便計(jì)算典型例題7.2×12.5＝9×（0.8×12.5）＝9×10＝902.5×0.23×0.4＝2.5×0.4×0.23＝1×0.23＝0.2312.5×7.4×8＝12.5×8×7.4＝100×7.4＝7403.6×48＋3.6×52＝3.6×（48＋52）＝3.6×100＝3602.5×0.23×4＝2.5×4×0.23＝10×0.23＝2.33.9×3.5＋3.5×6.1＝（3.9＋6.1）×3.5＝10×3.5＝3528×0.25＝7×4×0.25＝7×（4×0.25）＝7×1＝75.6×99＋5.6＝5.6×99＋5.6×1＝5.6×（99＋1）＝5.6×100＝56088×0.25×9＝8×11×0.25×9＝(8×0.25)×(11×9)＝2×99＝198五上數(shù)學(xué)小數(shù)乘法簡(jiǎn)便計(jì)算典型例題4.9×1.02＝4.9×（1＋0.02）＝4.9＋4.9×0.02＝4.9＋0.098＝4.998 3.7×102＝3.7×（100＋2）＝3.7×100＋3.7×2＝370＋7.4＝377.4 46.7×99＋46.7＝46.7×99＋46.7×1＝46.7×（99＋1）＝46.7×100＝46704×125×2.5×8＝8×125×（2.5×4）＝1000×10＝1000018.9×7.9＋18.9×2.1＝18.9×（7.9＋2.1）＝18.9×10＝189（125＋2.5）×0.8＝125×0.8＋2.5×0.8＝100＋2＝1021.7×101＝1.7×（100＋1）＝1.7×100＋1.7×1＝170＋1.7＝171.78.6×10.1＝8.6×（10＋0.1）＝8.6×10＋8.6×0.1＝86＋0.86＝86.860.45×99＝0.45×（100－1）＝0.45×100－0.45×1＝45－0.45＝44.559.25×101－9.25＝9.25×101－9.25×1＝9.25×（101－1）＝9.25×100＝925125