计算下面各题. (76÷4+31)×40492÷(4.3×2-0.4)35×÷-12
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解:(1)(76÷4+31)×40,
=(19+31)×40,
=50×40,
=2000;
(2)492÷(4.3×2-0.4),
=492÷(8.6-0.4),
=492÷8.2,
=60;
(3)35×÷-12,
=35××-12,
=48-12,
=36;
(4)÷[×(+)],
=÷[×],
=÷,
=×10,
=.
解析分析:(1)先算括号内的除法,再算括号内的加法,最后算括号外的乘法;
(2)先算括号内的乘法,再算括号内的减法,最后算括号外的除法;
(3)把除法改为乘法,先算乘法,再算减法;
(4)先算小括号内的,再算中括号内的,最后算括号外的.
点评:此题考查了整数、小数、分数的四则混合运算,注意运算顺序和运算法则.