题目内容
用简便方法计算.
| (
| ||||||||||||
|
|
(1)
×
×
=
×
=
;
(2)(
-
)×
=
×
-
×
=
-
=
;
(3)
×
+
×
=(
+
)×
=1×
=
;
(4)
×29+
=
×(29+1)
=
×30
=23.
5 |
7 |
14 |
15 |
3 |
8 |
=
2 |
3 |
3 |
8 |
=
1 |
4 |
(2)(
1 |
3 |
1 |
9 |
27 |
31 |
=
1 |
3 |
27 |
31 |
1 |
9 |
27 |
31 |
=
9 |
31 |
3 |
31 |
=
6 |
31 |
(3)
8 |
9 |
3 |
4 |
1 |
9 |
3 |
4 |
=(
8 |
9 |
1 |
9 |
3 |
4 |
=1×
3 |
4 |
=
3 |
4 |
(4)
23 |
30 |
23 |
30 |
=
23 |
30 |
=
23 |
30 |
=23.
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