计算下面各题,能简算的要简算7.65-0.65×69.43-1.68-4.321.25×0.76×0.80.32×7.5-0.32×4.53.8×10.19.9÷[

发布时间:2020-07-30 19:11:44

计算下面各题,能简算的要简算 7.65-0.65×69.43-1.68-4.321.25×0.76×0.80.32×7.5-0.32×4.53.8×10.19.9÷[16.5-(1.7+3.8)].

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解:(1)7.65-0.65×6,
=7.65-3.9,
=3.75;

(2)9.43-1.68-4.32,
=9.43-(1.68+4.32),
=9.43-6,
=3.43;

(3)1.25×0.76×0.8,
=(1.25×0.8)×0.76,
=1×0.76,
=0.76;

(4)0.32×7.5-0.32×4.5,
=0.32×(7.5-4.5),
=0.32×3,
=0.96;

(5)3.8×10.1,
=3.8×(10+0.1),
=38+0.38,
=38.38;

(6)9.9÷[16.5-(1.7+3.8)],
=9.9÷[16.5-5.5],
=9.9÷11,
=0.9.
解析分析:(1)先算乘法,再算减法;(2)运用减法的性质简算;(3)运用乘法交换律与结合律简算;(4)运用乘法分配律简算;(5)把10.1看作10+0.1,运用分配律简算;(6)先算小括号内的,再算中括号内的,最后算括号外的.

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律简便计算.
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