题目内容

简便运算
(1)
2
3
+(
4
7
+
1
2
)×
7
25
;        (2)
5
12
÷[
5
6
-(
3
8
+
1
4
)];
(3)36
4
7
÷4;                (4)55×(
7
44
+
7
22
);
(5)8.5×
1
4
+8
1
2
×0.75+8.5;   (6)3×(
2
15
+
1
12
)-
2
5

(7)
2
9
×
3
4
+0.75+
7
9
×75%;     (8)
6
7
×
4
15
+
3
7
÷
15
4
+
4
15
÷
7
12

(9)(1-75%)÷(1+
1
4
);    (10)
19
25
×8+
6
25
×8+
2
25
+
2
25
+
2
25
考点:整数、分数、小数、百分数四则混合运算,运算定律与简便运算
专题:运算顺序及法则,运算定律及简算
分析:(1)首先计算小括号里面的,然后计算乘法,最后计算加法即可;
(2)首先计算小括号里面的,然后计算中括号里面的,最后计算中括号外面的即可;
(3)根据除法的性质简算即可;
(4)(5)(6)(7)(8)(10)根据乘法分配律简算即可;
(9)首先计算小括号里面的,然后计算除法即可.
解答: 解:(1)
2
3
+(
4
7
+
1
2
)×
7
25

=
2
3
+
15
14
×
7
25

=
2
3
+
3
10

=
29
30


(2)
5
12
÷[
5
6
-(
3
8
+
1
4
)]
=
5
12
÷[
5
6
-
15
24
]
=
5
12
÷
5
24

=2

(3)36
4
7
÷4
=(36+
4
7
)÷4
=36÷4+
4
7
÷4
=9+
1
7

=9
1
7


(4)55×(
7
44
+
7
22

=55×
7
44
+55×
7
22

=26.25

(5)8.5×
1
4
+8
1
2
×0.75+8.5
=8.5×(
1
4
+0.75+1)
=8.5×2
=17

(6)3×(
2
15
+
1
12
)-
2
5

=3×
2
15
+3×
1
12
-
2
5

=
2
5
+
1
4
-
2
5

=
2
5
-
2
5
+
1
4

=
1
4



(7)
2
9
×
3
4
+0.75+
7
9
×75%
=
2
9
×0.75+0.75+
7
9
×0.75
=(
2
9
+1+
7
9
)×0.75
=2×0.75
=1.5

(8)
6
7
×
4
15
+
3
7
÷
15
4
+
4
15
÷
7
12

=
6
7
×
4
15
+
3
7
×
4
15
+
4
15
×
12
7

=(
6
7
+
3
7
+
12
7
)×
4
15

=3×
4
15

=
4
5


(9)(1-75%)÷(1+
1
4

=0.25÷1.25
=0.2

(10)
19
25
×8+
6
25
×8+
2
25
+
2
25
+
2
25

=(
19
25
+
6
25
)×8+
2
25
×3
=8+
6
25

=8
6
25
点评:此题主要考查了整数、分数、小数四则混合运算,注意运算顺序,注意乘法运算定律的应用.
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