题目内容
下面各题怎样算简便就怎样算. (1)
|
(2)0.8+
|
(3)(
| ||||||||||||||||||
(4)
|
(5)(0.25+
|
(6)
|
分析:(3)运用乘法分配律简算,其余题目按照先算乘除,再算加减,有括号的先算括号里面的顺序计算.
解答:解:(1)
×
÷
,
=
×
×
,
=
;
(2)0.8+
÷
,
=0.8+0.6,
=1.4;
(3)(
+
)×56,
=56×
+
×56,
=32+21,
=53;
(4)
+
+
×
,
=
+
+
,
=
+
,
=
;
(5)(0.25+
)×(1.6÷
),
=
×2,
=
;
(6)
×[1÷(
+
)],
=
×(1÷
),
=
×
,
=
.
4 |
9 |
9 |
14 |
4 |
21 |
=
4 |
9 |
9 |
14 |
21 |
4 |
=
3 |
2 |
(2)0.8+
1 |
2 |
5 |
6 |
=0.8+0.6,
=1.4;
(3)(
4 |
7 |
3 |
8 |
=56×
4 |
7 |
3 |
8 |
=32+21,
=53;
(4)
3 |
8 |
4 |
7 |
1 |
4 |
2 |
5 |
=
3 |
8 |
4 |
7 |
1 |
10 |
=
53 |
56 |
1 |
10 |
=
293 |
280 |
(5)(0.25+
1 |
3 |
4 |
5 |
=
7 |
12 |
=
7 |
6 |
(6)
3 |
4 |
5 |
6 |
3 |
4 |
=
3 |
4 |
19 |
12 |
=
3 |
4 |
12 |
19 |
=
9 |
19 |
点评:乘法分配律是常用的简算方法,要灵活运用.
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