计算(能够简算的要简算)
5400-2940÷28389×42.7+389×57.3(+)÷4+1÷(0.75+)×+++.
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解:(1)5400-2940÷28,
=5400-105,
=5400-(100+5),
=5400-100-5,
=5295;
(2)389×42.7+389×57.3,
=389×(42.7+57.3),
=389×100,
=38900;
(3)(+)÷4+,
=×+,
=+,
=;
(4)1÷(0.75+)×,
=1÷(+)×,
=1÷×,
=×,
=;
(5)+++,
=(+)+(+),
=1+1,
=2.
解析分析:(1)按运算顺序计算,先算除法,再算减法;(2)运用乘法分配律的逆运算简算;(3)先算小括号内的再算括号外的除法,最后算加法;(4)把0.75化为分数,先算括号内的,再算括号外的除法,最后算乘法;(5)运用加法交换律和结合律简算.
点评:此题主要考查分数、整数、小数的四则混合运算的运算顺序和应用运算定律进行简便计算.