题目内容

用简便方法计算.
(1)30×(
1
3
+
1
5
)
(2)
5
6
×7+
1
6
×7
(3)93×
9
92
(4)
2
7
+
2
7
×13
(5)
1
8
×
5
7
-
1
8
×
4
7
(6)
8
15
-
4
5
×
8
15
(7)
2
3
×
3
13
×6×26
(8)82×
3
11
×
1
41
.
分析:(1)、(2)、(3)、(4)、(5)、(6)根据乘法分配律进行简算;
(7)根据乘法交换律和结合律进行简算;
(8)根据乘法交换律进行简算.
解答:解:
(1)30×(
1
3
+
1
5
),
=30×
1
3
+30×
1
5
,
=10+6,
=16;

(2)
5
6
×7+
1
6
×7,
=(
5
6
+
1
6
)×7,
=7;

(3)93×
9
92
,
=(92+1)×
9
92
,
=92×
9
92
+1×
9
92
,
=9+
9
92
,
=9
9
92
,

(4)
2
7
+
2
7
×13,
=
2
7
×(1+13),
=
2
7
×14,
=4;

(5)
1
8
×
5
7
-
1
8
×
4
7
,
=
1
8
×(
5
7
-
4
7
),
=
1
8
×
1
7
,
=
1
56
;

(6)
8
15
-
4
5
×
8
15
,
=
8
15
×(1-
4
5
),
=
8
15
×
1
5
,
=
8
75
;

(7)
2
3
×
3
13
×6×26,
=(
2
3
×6)×(
3
13
×26),
=4×6,
=24;

(8)82×
3
11
×
1
41
,
=82×
1
41
×
3
11
,
=2×
3
11
,
=
6
11
.
点评:完成本题要注意分析式中数据,运用合适的简便方法计算.
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