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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