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0.8×0.9≈0.72.
错误
分析:求出0.8×0.9的准确值,再进行比较.据此解答.
解答:0.8×0.9=0.72,0.72是0.8与0.9乘积的准确值.所以要用等于号,不能用约等于号.
故答案为:×.
点评:本题主要考查了学生对准确值和近似值知识的掌握情况.
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5600
5600
        3.7×0.5=
1.85
1.85
     3.2×100=
320
320
      8.9-3.8=
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5.1

(2)3.8+2.5+6.2=
12.5
12.5
    12-6.2-3.8=
2
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   1.7+0.43+3.3=
5.43
5.43
    3.4-1.5-0.5=
1.4
1.4

(3)
8
9
+
1
9
--
2
7
=
5
7
5
7
     1.4×5=
7
7
    650-470=
180
180
    79+2.1=
81.1
81.1
    
(4)3.14×3=
9.42
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10.1
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6
13
+
7
13
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1
1

(5)3.99+5.2=
9.19
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   23+6.68=
29.68
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0.56
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0.1
0.1

(6)22×0.2=
4.4
4.4
   99.9+1=
100.9
100.9
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0.12
0.12
   3.9÷1.3=
3
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(7)0.8×0.8=
0.64
0.64
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4
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   26÷2.6=
10
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(8)340÷17=
20
20
   9.3÷0.3=
31
31
  13×4=
52
52
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18
18

(9)1.5×4=
6
6
   20×16=
320
320
   28×3=
84
84
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0.8
0.8
 
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28
28
   3200÷1000=
3.2
3.2
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50
50
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(11)340+120=
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1
4
+
1
2
=
3
4
3
4
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0.5
0.5
   4.95×10=
49.5
49.5
   
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1
2
-
1
2
=
11
11
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4
4
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0.65
0.65
   12×0.05=
0.6
0.6

(13)3.08÷0.1=
30.8
30.8
   0.35×6=
2.1
2.1
   25÷0.5=
50
50
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4.5
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(14)4.3-2.7=
1.6
1.6
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9
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10
10
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2
9
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4
9
=
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3
1
3
12
11
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1
11
=
1
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1
        
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0.92
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22
22
           
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0.42
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0.43
0.43
         
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0.744
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5.1
5.1
        
99+0.1﹦
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1.2
1.2
              
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6
6
1.9×4﹦
7.6
7.6
            
8.8÷0.11=
80
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1.2
1.2
       
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10
10
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72
72
             
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