题目内容

计算下面各题,能简算的要简算.
(1)10÷8+3.96×12.5%+2.04×
2
16
 
(2)6000-105×36
(3)85-84
7
8
÷7                               
(4)
4
15
÷[(
4
7
+
4
21
7
12
]

(5)1
6
7
×3.6+3
3
5
×7
1
7
+3.6
分析:(1)据乘法算式的性质将原式变为0.125×10+3.96×12.5%+2.04×0.125后再据分配律进行简便运算;
(2)根据分配律将105×36变为(100+5)×36再据减法性质进行计算;
(3)可先据分配律将式中84
7
8
÷7拆分为(84+
7
8
)÷7再据减法性质进行简便计算;
(4)可将括号中的算式据分配律进行简便计算;
(5)将据分配律进行简便计算.
解答:解:(1)10÷8+3.96×12.5%+2.04×
2
16
 
=1.25+3.96×12.5%+2.04×0.125,
=0.125×10+3.96×0.125+2.04×0.125,
=(10+3.96+2.04)×0.125,
=16×0.125,
=2;
(2)6000-105×36
=6000-(100+5)×36,
=6000-100×36-36×5,
=6000-3600-180,
=2220;
(3)85-84
7
8
÷7
=85-(84+
7
8
)÷7,
=85-84÷7-
7
8
÷
7,
=85-12-
1
8

=72
7
8

(4)
4
15
÷[(
4
7
+
4
21
7
12
]

=
4
15
÷[
4
7
×
7
12
+
4
21
×
7
12
],
=
4
15
÷[
1
3
+
1
9
],
=
4
15
×
9
4

=
3
5

(5)1
6
7
×3.6+3
3
5
×7
1
7
+3.6

=1
6
7
×3.6+3.6×7
1
7
+3.6,
=(1
6
7
+7
1
7
+1)×3.6,
=10×3.6,
=36.
点评:完成此类题目要认真分析式中据,根据式中数据的特点及内在联系选择合适的方法进行简便计算.
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