题目内容

计算
(1)3
8
11
×1.25×2
1
2
×3.2

(2)35
5
9
×29+65
5
9
×29-
1
9
÷
1
29

(3)0.03÷[(14-2.25×
8
15
)÷60%]

(4)2
5
6
×0.65+2
5
6
×0.35-(2
2
5
+0.72)÷2
22
25

(5){[4-(2
1
7
-1
1
5
)×3.5
]÷0.16-2
3
16
(2
22
84
-1
49
60
)
分析:(1)先把3.2分解成8×0.4,再运用乘法结合律简算;
(2)先把除法变成乘法,然后两次运用乘法分配律简算;
(3)先算小括号里面的乘法,再算小括号里面的减法,然后算中括号里面的除法,最后算括号外的除法;
(4)先算小括号里面的加法,再运用乘法分配律简算;
(5)先运用乘法分配律计算中括号里面的运算,再算大括号里面的除法,然后算大括号里面的减法,最后再运用乘法分配律简算.
解答:解:(1)3
8
11
×1.25×2
1
2
×3.2

=3
8
11
×(1.25×2.5×0.4×8),
=3
8
11
×[(1.25×8)×(2.5×0.4)],
=3
8
11
×(10×1),
=3
8
11
×10,
=
410
11


(2)35
5
9
×29+65
5
9
×29-
1
9
÷
1
29

=35
5
9
×29+65
5
9
×29-
1
9
×29,
=(35
5
9
+65
5
9
-
1
9
)×29,
=101×29,
=(100+1)×29,
=100×29+1×29,
=2900+29,
=2929;

(3)0.03÷[(14-2.25×
8
15
)÷60%]

=0.03÷[(14-1.2)÷0.6],
=0.03÷[12.8÷0.6],
=0.03÷
64
3

=
9
6400


(4)2
5
6
×0.65+2
5
6
×0.35-(2
2
5
+0.72)÷2
22
25

=2
5
6
×0.65+2
5
6
×0.35-3.12÷2
22
25

=2
5
6
×(0.65+0.35)-3.12÷2
22
25

=2
5
6
×1-3.12÷2
22
25

=2
5
6
-1
1
12

=1
3
4


(5){[4-(2
1
7
-1
1
5
)×3.5
]÷0.16-2
3
16
(2
22
84
-1
49
60
)

={[4-(
15
7
×3.5-
6
5
×3.5)]÷0.16-2
3
16
(2
22
84
-1
49
60
)

={[4-(7.5-4.2)]÷0.16-2
3
16
(2
22
84
-1
49
60
)

={[4-3.3]÷0.16-2
3
16
(2
22
84
-1
49
60
)

={0.7÷0.16-2
3
16
(2
22
84
-1
49
60
)

={
70
16
-
35
16
(2
22
84
-1
49
60
)

=
35
16
×(2
22
84
-1
49
60
)

=
35
16
×
95
42
-
35
16
×
109
60

=
475
96
-
545
192

=
192
405
点评:本题计算较复杂,要注意分析式中数据,运用合适的简便方法计算.
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