题目内容
灵活计算下面各题
1.25×0.32×250 |
|
|
86×(
|
分析:①1.25×0.32×250,转化为:1.25×8×0.04×250,再运用乘法结合律进行简算;
②
-
÷
-
,把除数转化为乘它的倒数,再根据减法的运算性质进行简算;
③
×2009,转化为:
×(2010-1),再运用乘法分配律进行简算;
④86×(
-
)×3,运用乘法分配律进行简算.
②
20 |
19 |
1 |
3 |
3 |
5 |
4 |
9 |
③
2009 |
2010 |
2009 |
2010 |
④86×(
5 |
6 |
2 |
3 |
解答:解:①1.25×0.32×250,
=(1.25×8)×(0.04×250),
=10×10,
=100;
②
-
÷
-
,
=
-
×
-
,
=
-(
+
),
=
-1,
=
;
③
×2009,
=
×(2010-1),
=
×2010-
×1,
=2009-
,
=2008
;
④86×(
-
)×3,
=86×
×3-86×
×3,
=205-172,
=33.
=(1.25×8)×(0.04×250),
=10×10,
=100;
②
20 |
19 |
1 |
3 |
3 |
5 |
4 |
9 |
=
20 |
19 |
1 |
3 |
5 |
3 |
4 |
9 |
=
20 |
19 |
5 |
9 |
4 |
9 |
=
20 |
19 |
=
1 |
19 |
③
2009 |
2010 |
=
2009 |
2010 |
=
2009 |
2010 |
2009 |
2010 |
=2009-
2009 |
2010 |
=2008
1 |
2010 |
④86×(
5 |
6 |
2 |
3 |
=86×
5 |
6 |
2 |
3 |
=205-172,
=33.
点评:此题考查的目的是理解掌握乘法的运算定律和减法的运算性质,并且能够运用这些运算定律和运算性质进行简便计算.
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