题目内容
| 下面各题,怎样简便就怎样算. 2-
|
0.37+
| ||||||||||||||||
|
|
分析:(1)运用减法的性质简算;
(2)(3)运用加法交换律与结合律简算;
(4)运用减法的性质以及加法交换律与结合律简算.
(2)(3)运用加法交换律与结合律简算;
(4)运用减法的性质以及加法交换律与结合律简算.
解答:解:(1)2-
-
-
=2-(
+
+
)
=2-(
+
)
=2-1
=1;
(2)0.37+
+0.63+
=(0.37+0.63)+(
+
)
=1+1
=2;
(3)
+
+
+
=(
+
)+(
+
)
=1+1
=2;
(4)
-(
+
)+
=
-
-
+
=(
-
)-(
-
)
=
.
| 1 |
| 2 |
| 1 |
| 3 |
| 1 |
| 6 |
=2-(
| 1 |
| 2 |
| 1 |
| 3 |
| 1 |
| 6 |
=2-(
| 5 |
| 6 |
| 1 |
| 6 |
=2-1
=1;
(2)0.37+
| 3 |
| 5 |
| 2 |
| 5 |
=(0.37+0.63)+(
| 3 |
| 5 |
| 2 |
| 5 |
=1+1
=2;
(3)
| 4 |
| 7 |
| 1 |
| 9 |
| 3 |
| 7 |
| 8 |
| 9 |
=(
| 4 |
| 7 |
| 3 |
| 7 |
| 1 |
| 9 |
| 8 |
| 9 |
=1+1
=2;
(4)
| 7 |
| 9 |
| 1 |
| 2 |
| 2 |
| 9 |
| 1 |
| 2 |
=
| 7 |
| 9 |
| 1 |
| 2 |
| 2 |
| 9 |
| 1 |
| 2 |
=(
| 7 |
| 9 |
| 2 |
| 9 |
| 1 |
| 2 |
| 1 |
| 2 |
=
| 5 |
| 9 |
点评:注意观察题目中数字构成的特点和规律,善于灵活运用运算定律或运算技巧,巧妙解答.
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