题目内容

3
8
×
4
7
+
4
7
×
13
8
-
4
7
．
分析：把最后一个
4
7
化成
4
7
×1，再利用乘法分配律简算．
解答：解：
3
8
×
4
7
+
4
7
×
13
8
-
4
7
，
=
3
8
×
4
7
+
4
7
×
13
8
-
4
7
×1，
=（
3
8
+
13
8
-1）×
4
7
，
=1×
4
7
，
=
4
7
．
点评：乘法分配律是最常用的简便运算的方法，要熟练掌握，灵活运用．
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相关题目
口算：
4
7
+
4
7
=		 1.52=
13
8
-
7
8
=		 1.8÷2.7=
1
5
-
1
6
=
1
8
+
1
12
=		 4+
1
9
=		 3-
7
10
=
5
6
-
1
16
=
3
10
-
3
100
=
15
16
-
1
4
-
1
8
=
3
8
+
1
3
+
5
8
=
直接写数对又快
66+8=		 3.8+6.2=
4
9
×
3
8
=		 47-8= 3.8÷0.19=
12÷
3
7
=		 56÷4= 24×0.5= 1-
3
11
=		 471-299=
1÷0.25=
3
7
×
5
6
=		 600÷5= 8-0.8=
1
3
+
1
6
=
1.06×8×12.5= 1.5×0.6=
1
5
-
1
7
=		 6.6+4= 1.5÷0.3=
1
2
÷
3
4
=		 1-0.05=
2
9
×4=
2
9
+
2
3
=
6
7
÷3=
1
2
-
1
8
=		 2-
4
9
-
5
9
=
5
9
+
1
3
=		 1-
1
5
÷
3
5
 1+
7
8
÷
7
8
=
1
2
-
1
5
=
2
3
+
1
4
=
1
13
+
7
13
=
5
7
-
2
7
=
3
8
-
3
8
=
7
10
-
7
20
=
1
4
+
3
8
=
4
7
-
1
6
=
1-
1
5
-
2
5
=
5
9
+
4
9
=
（2012?石棉县模拟）
直接写出得数
1-
3
8
=
4
7
÷4=		 1÷
2
9
=
5
6
-
1
3
=
0.8×0.01= 1÷0.05= 1.6×0.25= 5.4÷60=
7
8
×
2
7
=
9
11
÷
9
22
=
1
5
+
3
8
=		 9-
5
13
-
3
13
=
直接写数对又快
66+8=		 3.8+6.2=
4
9
×
3
8
=		 47-8= 3.8÷0.19=
12÷
3
7
=		 56÷4= 24×0.5= 1-
3
11
=		 471-299=
1÷0.25=
3
7
×
5
6
=		 600÷5= 8-0.8=
1
3
+
1
6
=
1.06×8×12.5= 1.5×0.6=
1
5
-
1
7
=		 6.6+4= 1.5÷0.3=
1
2
÷
3
4
=		 1-0.05=
2
9
×4=
2
9
+
2
3
=
6
7
÷3=
1
2
-
1
8
=		 2-
4
9
-
5
9
=
5
9
+
1
3
=		 1-
1
5
÷
3
5
 1+
7
8
÷
7
8
=

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