题目内容
能简算的要简算
×7+
×5
1
+3
+5
+7
+9
36×(
+
-
)
2010÷2010
.
| 3 |
| 8 |
| 1 |
| 8 |
1
| 1 |
| 3 |
| 1 |
| 15 |
| 1 |
| 35 |
| 1 |
| 63 |
| 1 |
| 99 |
36×(
| 7 |
| 12 |
| 5 |
| 9 |
| 1 |
| 4 |
2010÷2010
| 2010 |
| 2011 |
分析:整数四则运算的运算定律或性质对于分数同样适用:
(1)、(3)利用乘法分配律进行简算;
(2)利用加法结合律,先把算式改写成(1+3+5+7+9)+(
+
+
+
+
)的形式,再把(
+
+
+
+
)改写成(1-
+
-
+
-
+
-
+
-
)÷2的形式进行简算;
(4)先把算式改写成2010×
,进而先约分再计算.
(1)、(3)利用乘法分配律进行简算;
(2)利用加法结合律,先把算式改写成(1+3+5+7+9)+(
| 1 |
| 3 |
| 1 |
| 15 |
| 1 |
| 35 |
| 1 |
| 63 |
| 1 |
| 99 |
| 1 |
| 3 |
| 1 |
| 15 |
| 1 |
| 35 |
| 1 |
| 63 |
| 1 |
| 99 |
| 1 |
| 3 |
| 1 |
| 3 |
| 1 |
| 5 |
| 1 |
| 5 |
| 1 |
| 7 |
| 1 |
| 7 |
| 1 |
| 9 |
| 1 |
| 9 |
| 1 |
| 11 |
(4)先把算式改写成2010×
| 2011 |
| 2010×(2011+1) |
解答:解:(1)
×7+
×5,
=
×(21+5),
=
×26.
=
;
(2)1
+3
+5
+7
+9
,
=(1+3+5+7+9)+(
+
+
+
+
),
=25+(1-
+
-
+
-
+
-
+
-
)÷2,
=25+(1-
)÷2,
=25+
,
=25
;
(3)36×(
+
-
),
=36×
+36×
-36×
,
=21+20-9,
=32;
(4)2010÷2010
;
=2010÷
,
=2010×
,
=2010×
,
=
.
| 3 |
| 8 |
| 1 |
| 8 |
=
| 1 |
| 8 |
=
| 1 |
| 8 |
=
| 13 |
| 4 |
(2)1
| 1 |
| 3 |
| 1 |
| 15 |
| 1 |
| 35 |
| 1 |
| 63 |
| 1 |
| 99 |
=(1+3+5+7+9)+(
| 1 |
| 3 |
| 1 |
| 15 |
| 1 |
| 35 |
| 1 |
| 63 |
| 1 |
| 99 |
=25+(1-
| 1 |
| 3 |
| 1 |
| 3 |
| 1 |
| 5 |
| 1 |
| 5 |
| 1 |
| 7 |
| 1 |
| 7 |
| 1 |
| 9 |
| 1 |
| 9 |
| 1 |
| 11 |
=25+(1-
| 1 |
| 11 |
=25+
| 5 |
| 11 |
=25
| 5 |
| 11 |
(3)36×(
| 7 |
| 12 |
| 5 |
| 9 |
| 1 |
| 4 |
=36×
| 7 |
| 12 |
| 5 |
| 9 |
| 1 |
| 4 |
=21+20-9,
=32;
(4)2010÷2010
| 2010 |
| 2011 |
=2010÷
| 2011×2010+2010 |
| 2011 |
=2010×
| 2011 |
| 2010×2011+2010 |
=2010×
| 2011 |
| 2010×(2011+1) |
=
| 2011 |
| 2012 |
点评:在计算四则混合运算题时,要注意根据题目中的数据的具体情况,合理的选用简便算法进行计算.
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