题目内容
计算下面各题.
6.2×(19.2÷3.2)×0.04;
[17.92-4×(0.78+0.46)]-0.72
4.05÷(20-17.5)×0.4;
(3.64-1.8)÷0.2×30.
6.2×(19.2÷3.2)×0.04;
[17.92-4×(0.78+0.46)]-0.72
4.05÷(20-17.5)×0.4;
(3.64-1.8)÷0.2×30.
分析:(1)(3)(4)先算括号内的,然后从左往右依次运算;
(2)先算小括号内的,再算中括号内的乘法,然后算中括号内的减法,最后算括号外的减法.
(2)先算小括号内的,再算中括号内的乘法,然后算中括号内的减法,最后算括号外的减法.
解答:解:(1)6.2×(19.2÷3.2)×0.04
=6.2×6×0.04
=1.488;
(2)[17.92-4×(0.78+0.46)]-0.72
=[17.92-4×1.24]-0.72
=[17.92-4.96]-0.72
=12.96-0.72
=12.24;
(3)4.05÷(20-17.5)×0.4
=4.05÷2.5×0.4
=1.62×0.4
=0.648;
(4)(3.64-1.8)÷0.2×30
=1.84÷0.2×30
=9.2×30
=276.
=6.2×6×0.04
=1.488;
(2)[17.92-4×(0.78+0.46)]-0.72
=[17.92-4×1.24]-0.72
=[17.92-4.96]-0.72
=12.96-0.72
=12.24;
(3)4.05÷(20-17.5)×0.4
=4.05÷2.5×0.4
=1.62×0.4
=0.648;
(4)(3.64-1.8)÷0.2×30
=1.84÷0.2×30
=9.2×30
=276.
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.
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