数学上册复习简便运算课件.ppt

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1、人教版五年级上册分宜县凤阳中心学校敖霞梅复习简便运算=125×0.8×1.3=(125×0.8)×1.3=100×1.3=130125×1.3×0.8=0.25×1.2×0.9=0.25×(4×0.3)×0.9=(0.25×4)×0.3×0.9=1×0.3×0.9=0.270.25×0.9×1.2=(200-1)×0.88=200×0.88-1×0.88=176-0.88=175.12199×0.8890×10.3=90×（10+0.3）=90×10+90×0.3=900+27=9272.37×15-2.37×5=2.37×（15-5）=2.37×10=2

2、3.79.7＋9.7×99=9.7×1+9.7×99=9.7×（1+99）=9.7×100=97010.9×6+109×0.4=109×0.6+109×0.4=109×（0.6+0.4）=109×1=10950.5÷2.5÷0.2=50.5÷（2.5×0.2）=50.5÷5=10.1括号前面是除号，去掉括号要变号，乘号变除号，除号变乘号2.4÷（3.6÷5）=2.4÷3.6×5=2.4×5÷3.6=12÷3.6=214.68-7.82-2.18=14.68-（7.82+2.18）=14.68-10=4.688.75+3.37-0.75+4.63=8.75-

3、0.75+3.37+4.63=(8.75-0.75)+(3.37+4.63)=8+8=16没有括号的同一级运算可以换位置13.75-（6.38+3.75）=13.75-6.38-3.75=(13.75-3.75)-6.38=10-6.38=3.6226.06-（9.06-5.6）=26.06-9.06+5.6=(26.06-9.06)+5.6=17+5.6=22.6特殊括号前面是减号，去掉括号要变号，加号变减号，减号变加号5.32-2.16-0.84=5.32-(2.16+0.84)=5.32-3=2.3214.4÷2.4÷3=14.4÷(2.4×3)=1

4、4.4÷7.2=212.3×19-123×0.9=123×1.9-123×0.9=123×（1.9-0.9）=123×1=1230.25×36=0.25×4×9=1×9=92.5×16×0.7=2.5×(4×4)×0.7=(2.5×4)×(4×0.7)=10×2.8=286.3×302=6.3×(300+2)=6.3×300+6.3×2=1890+12.6=1902.61.26×8+8×1.74=(1.26+1.74)×8=3×8=241.25×1.19×1.6=1.25×1.19×(8×0.2)=1.25×(8×0.2)×1.19=(1.25×8)×(0

5、.2×1.19)=10×0.238=2.381.25×2.5×32320÷1.25÷817.8÷(1.78×4)2.22×9.9＋6.66×6.7=1.25×2.5×(4×8)=(1.25×8)×(2.5×4)=10×10=100=320÷(1.25×8)=320÷10=32=17.8÷1.78÷4=1÷4=0.25=2.22×(3×3.3)+6.66×6.7=(2.22×3)×3.3+6.66×6.7=6.66×3.3+6.66×6.7=6.66×(3.3+6.7)=6.66×10=66.64.8×7.8＋78×0.5215.6×13.1－15.6－15

6、.6×2.1(1.25－0.125)×84.8－4.8×0.5=1.25×8-0.125×8=10-1=9=4.8×7.8+7.8×5.2=7.8×(4.8+5.2)=7.8×10=78=15.6×13.1-15.6×1-15.6×2.1=15.6×(13.1-1-2.1)=15.6×10=156=4.8×1-4.8×0.5=4.8×(1-0.5)=4.8×0.5=2.46.1-5.9+3.9-4.115.89+（6.75-5.89）31.2-（21.2-8.8）25.8-13.6-5.8-6.4