用簡便的方法計(jì)算.
2000÷125÷8
25×96
99×38+38
328-164+72-36
98+998+9998+8.
解:(1)2000÷125÷8,
=2000÷(125×8),
=2000÷1000,
=2;
(2)25×96,
=25×4×24,
=100×24,
=2400;
(3)99×38+38,
=(99+1)×38,
=100×38,
=3800;
(4)328-164+72-36,
=(328+72)-(164+36),
=400-200,
=200;
(5)98+998+9998+8,
=(100-2)+(1000-2)+(10000-2)+8,
=11100+(8-6),
=11100+2,
=11102.
分析:(1)運(yùn)用除法的性質(zhì)簡算;
(2)根據(jù)數(shù)字特點(diǎn),把96看作4×24,運(yùn)用乘法結(jié)合律簡算;
(3)把38看作38×1,運(yùn)用乘法分配律的逆運(yùn)算簡算;
(4)運(yùn)用加法交換律和結(jié)合律以及減法的性質(zhì)簡算;
(5)把98看作100-2,998看作1000-2,9998看作10000-2.
點(diǎn)評:此題是考查整數(shù)四則混合運(yùn)算,要仔細(xì)觀察算式的特點(diǎn),靈活運(yùn)用一些定律進(jìn)行簡便計(jì)算.