题目内容

能简便的用简便方法计算.
88×4.9+5.1×0.88
2.5×8×0.4×0.125 0.65×201
36÷0.8-12.9 0.25×1.25×3.2 7.28+3.2÷2.5.
分析:(1)此题不适宜用乘法分配律简算,应先算乘法,再算加法;
(2)运用乘法交换律与结合律简算;
(3)把201看作200+1,运用乘法分配律简算;
(4)先算除法,再算减法;
(5)把3.2看作4×0.8,运用乘法交换律与结合律简算;
(6)先算除法,再算加法.
解答:解:(1)88×4.9+5.1×0.88
=431.2+4.488
=435.688;

(2)2.5×8×0.4×0.125
=(2.5×0.4)×(8×0.125)
=1×1
=1;

(3)0.65×201
=0.65×(200+1)
=0.65×200+0.65
=130+0.65
=130.65;

(4)36÷0.8-12.9
=45-12.9
=32.1;

(5)0.25×1.25×3.2
=0.25×1.25×4×0.8
=(0.25×4)×(1.25×0.8)
=1×1
=1;

(6)7.28+3.2÷2.5
=7.28+1.28
=8.56.
点评:此题考查了小数的四则混合运算,注意运算顺序和运算法则,灵活运用所学的运算定律简便计算.
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