用脱式计算.
18.5+4.1×7.2-9.5
10.48+22.56÷4.7×5.4
18-(1.4-1.25×0.8)
0.8×[13-(3.12+5.28)].
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解:(1)18.5+4.1×7.2-9.5,
=18.5+29.52-9.5,
=48.02-9.5,
=38.52;
(2)10.48+22.56÷4.7×5.4,
=10.48+4.8×5.4,
=10.48+25.92,
=36.4;
(3)18-(1.4-1.25×0.8),
=18-(1.4-1),
=18-0.4,
=17.6;
(4)0.8×[13-(3.12+5.28)],
=0.8×[13-8.4],
=0.8×4.6,
=3.68.
解析分析:(1)先算乘法,再算加法和减法;
(2)先算除法和乘法,再算加法;
(3)先算括号内的乘法,再算括号内的减法,最后算括号外的减法;
(4)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.