题目内容

计算.能简算的要简算,并写出简算过程.
(1)(0.12+0.22+0.32+0.422÷(0.13+0.23+0.33+0.43
(2)3.97÷7+
1
7
×4.03-
1
7
    
(3)0.0021×[1
6
7
+2.93÷(11
2
3
-1.9)]÷0.001
(4)0.125×0.25×0.5×64       
(5)4936×(0.75×42.7-0.573×25+57.3)÷3.
分析:(1)(0.12+0.22+0.32+0.422÷(0.13+0.23+0.33+0.43),根据平方、立方的意义,及小数四则混合运算的计算法则进行计算.

(2)3.97÷7+
1
7
×4.03-
1
7
,把除数转化为乘它的倒数,再运用乘法分配律进行简算; 

(3)0.0021×[1
6
7
+2.93÷(11
2
3
-1.9)]÷0.001,根据小数、分数四则混合运算的顺序,按照小数、分数四则运算的计算法则进行计算;

(4)0.125×0.25×0.5×64,把64分解为:8×4×2,然后运用乘法交换律和结合律进行简算;
  
(5)4936×(0.75×42.7-0.573×25+57.3)÷3.根据小数四则混合运算的顺序,按照小数四则运算的计算法则进行计算.
解答:解:(1)(0.12+0.22+0.32+0.422÷(0.13+0.23+0.33+0.43),
=(0.01+0.04+0.09+0.16)2÷(0.001+0.008+0.027+0.064),
=0.32÷0.1,
=0.09÷0.1,
=0.9;

(2)3.97÷7+
1
7
×4.03-
1
7

=3.97×
1
7
+
1
7
×4.03-
1
7

=(3.97+4.03-1)×
1
7

=7×
1
7

=1;

(3)0.0021×[1
6
7
+2.93÷(11
2
3
-1.9)]÷0.001,
=0.0021×[1
6
7
+2
93
100
÷
9
23
30
]÷0.001,
=0.0021×[1
6
7
+
293
100
×
30
293
]÷0.001,
=0.0021×[1
6
7
+
3
10
]÷0.001,
=0.0021×
151
70
÷0.001,
=0.00453÷0.001,
=4.53;

(4)0.125×0.25×0.5×64,
=0.125×0.25×0.5×8×4×2,
=(0.125×8)×(0.25×4)×(0.5×2),
=1×1×1,
=1;

(5)4936×(0.75×42.7-0.573×25+57.3)÷3.
=4936×(32.025-14.325+57.3)÷3,
=4936×75÷3,
=370200÷3,
=123400.
点评:此题考查的目的是掌握整数、小数、分数四则混合运算的顺序,以及它们的计算法则,并且能够灵活选择简便方法计算进行计算.
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