题目内容

3
8
+
1
8
=
5
9
-
2
9
=
5
6
-
5
6
=
1
3
+
1
2
=
1-
5
8
=
7
10
+
5
10
=
3
4
-
1
2
=
3
4
-
3
4
=
5
11
+
4
11
=
分析：同分母分数相加减，分子不变，分母相加减；
异分母分数相加减，先通分，变成同分母的分数相加减，再计算．
解答：解：
3
8
+
1
8
=
1
2
，
5
9
-
2
9
=
1
3
，
5
6
-
5
6
=0，
1
3
+
1
2
=
5
6
，
1-
5
8
=
3
8
，
7
10
+
5
10
=
6
5
，
3
4
-
1
2
=
1
4
，
3
4
-
3
4
=0，
5
11
+
4
11
=
9
11
．
点评：本题考查了分数的加减法，计算时要细心，注意把结果化成最简分数．
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39×303≈		 215×38≈ 48×299≈ 180×31≈
208×40≈ 5.2×391≈ 328×18≈ 18×59≈
99×201≈
用递等式计算．
16×[125÷（251-226）]
25×35×120
5600÷[（38+18）×2]
59×（481-279）
直接写出得数．
12×
5
9
=
6
25
÷
3
5
=
3
8
×
4
21
=
2
5
+
3
5
×
2
3
=
18÷
2
9
=		 2-75%=
12
13
÷8=		 ( 
4
9
-
1
5
)×45=
（2006?资中县）
146+38= 126-70= 2.3+4.68= 5.23-2.2=
9÷1.5= 2.25×4= 30×20%= 6.4÷0.8=
1
8
-
1
9
=
2
3
+
2
9
=
8
9
×
3
4
=
5
9
÷
2
3
=
3-
2
7
-
5
7
=		 （
1
6
+
2
3
）×3=
2
3
×
9
8
×
1
2
=
2
3
×6+6×
1
3
=
3
4
5
-2.7=		 14×
2
7
=		  
15
16
÷5=
 1
1
3
÷
1
3
=
1
2
×
1
5
×
1
4
=		 0÷2
2
7
×9
1
5
=
 
1
3
+3÷
1
2
=		  
7
15
-
2
5
=
1
2
+
1
4
=
 4÷
2
3
=
9
14
-
9
14
=		  
3
4
+
1
3
=
7
12
×
3
14
=		 24÷
3
8
=		  
3
10
×
5
9
=
 
1
5
÷3=		 4-
2
5
=
1
5
÷3=
9
14
-
7
14
=		  
1
3
+3÷
1
2
=		 5-
3
4
=
2
3
8
×9
1
5
×0=		  
1
3
÷
1
6
=		  
1
3
×
1
4
×
1
2
=
3
10
×
5
6
=		  
1
6
×3=		  
3
8
+85+
5
8
=
4-
7
8
-
1
8
=
7
9
-
1
3
=		  
3
4
÷
1
2
=
 0.25×8= 3.4-
8
13
-
5
13
=
1
3
+0.5=
10.5-1.05=  
3
10
×
5
12
=		 10.01÷10%=
1.5×
3
5
=		  
4
5
÷80%=		  1×9÷
1
9
=
3×
1
3
÷
3
4
÷4=

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