下面各題,能用簡算的要用簡便計(jì)算.
1.85×2.5+2.15×2.5
81.99÷0.9×0.17
18.26-2.35-4.65
1.25×32×0.25
31.6÷1.25÷8
4.2÷0.7÷6
21.63-13.8×0.15
6.3÷3.5.
解:(1)1.85×2.5+2.15×2.5
=(1.85+2.15)×2.5,
=4×2.5,
=10;
(2)81.99÷0.9×0.17
=91.1×0.17,
=15.487;
(3)18.26-2.35-4.65
=18.26-(2.35+4.65),
=18.26-7,
=11.26;
(4)1.25×32×0.25
=(1.25×8)×(4×0.25),
=10×1,
=10;
(5)31.6÷1.25÷8
=31.6÷(1.25×8),
=31.6÷10,
=3.16;
(6)4.2÷0.7÷6
=4.2÷(0.7×6),
=4.2÷4.2,
=1;
(7)21.63-13.8×0.15
=21.63-2.07,
=19.56;
(8)6.3÷3.5
=6.3÷0.7÷5,
=9÷5,
=1.8.
分析:本題據(jù)四則混合運(yùn)算法則計(jì)算即可,同時(shí)要認(rèn)真分析式中數(shù)據(jù),盡量用簡便方法計(jì)算.
點(diǎn)評:完成此類有關(guān)于小數(shù)的四則混合運(yùn)算題目要注意小數(shù)點(diǎn)位置的變化.