用簡便方法計算.
99×2.45
5.6÷1.6
1.25×32+215×9.76×0
9.85×2.3-8.85×2.3.
解:(1)99×2.45,
=(100-1)×2.45,
=245-2.45,
=242.55;
(2)5.6÷1.6,
=5.6÷(4×0.4),
=5.6÷4÷0.4,
=1.4÷0.4,
=3.5;
(3)1.25×32+215×9.76×0,
=(1.25×8)×4+0,
=10×4,
=40;
(4)9.85×2.3-8.85×2.3,
=(9.85-8.85)×2.3,
=1×2.3,
=2.3.
分析:(1)把99看作(100-1),運用乘法分配律簡算;
(2)把16看作4×0.4,運用除法的性質簡算;
(3)把32看作8×4,運用乘法分配律計算1.25×32,因為任何數乘0都得0,因此215×9.76×0=0;
(4)運用除法的性質簡算.
點評:完成此題,應認真分析式中數據,運用合適的簡便算法計算.