题目内容

下面各题怎样算简便就怎样算.
7
9
×16×
27
7
7
12
-
5
18
)×36
1
3
+3÷
1
2
7
18
×
1
4
+
3
4
÷
18
7
2-
3
8
÷
7
16
-
1
7
1
7
+
6
7
×(
2
3
-0.25)
分析:(1)根据乘法交换律和结合律进行简算;
(2)根据乘法分配律进行简算;
(3)先算除法,再算加法;
(4)根据乘法分配律进行简算;
(5)先算除法,再算减法;
(6)先算小括号内的减法,再算乘法,最后算加法.
解答:解:(1)
7
9
×16×
27
7

=(
7
9
×
27
7
)×16,
=3×16,
=48;

(2)(
7
12
-
5
18
)×36,
=
7
12
×36-
5
18
×36,
=21-10,
=11;

(3)
1
3
+3÷
1
2

=
1
3
+6,
=6
1
3


(4)
7
18
×
1
4
+
3
4
÷
18
7

=
7
18
×
1
4
+
3
4
×
7
18

=
7
18
×(
1
4
+
3
4
),
=
7
18
×1,
=
7
18


(5)2-
3
8
÷
7
16
-
1
7

=2-
6
7
-
1
7

=2-(
6
7
+
1
7
),
=2-1,
=1;

(6)
1
7
+
6
7
×(
2
3
-0.25)

=
1
7
+
6
7
×
5
12

=
1
7
+
5
14

=
1
2
点评:四则混合运算,先弄清运算顺序,然后再进行计算,能简算的要简算.
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