题目内容
(2011?无锡)
用自己喜欢的方法计算. (1)(20-1.25×0.8)÷1.9 |
(2)(
| ||||||
(3)378-26-74 | (4)1.25×32×25 | ||||||
(5)1+0.45÷0.9-
|
(6)8.34×17-7×8.34. |
分析:(1)按计算法则进行计算;
(2)、(6)运用乘法分配律进行简算;
(3)连减两个数,等于减去这两个数的和;
(4)把32分解成8×4,然后运用乘法结合律进行简算;
(5)按计算法则进行计算,把分数化成小数计算.
(2)、(6)运用乘法分配律进行简算;
(3)连减两个数,等于减去这两个数的和;
(4)把32分解成8×4,然后运用乘法结合律进行简算;
(5)按计算法则进行计算,把分数化成小数计算.
解答:解:(1)(20-1.25×0.8)÷1.9,
=(20-1)÷1.9,
=19÷1.9,
=10;
(2)(
+
-
)×24,
=
×24+
×24-
×24,
=20+12-16,
=16;
(3)378-26-74,
=378-(26+74),
=378-100,
=278;
(4)1.25×32×25,
=1.25×8×4×25,
=(1.25×8)×(4×25),
=10×100,
=1000;
(5)1+0.45÷0.9-
,
=1+0.5-0.875,
=1.5-0.875,
=0.625;
(6)8.34×17-7×8.34,
=8.34×(17-7),
=8.34×10,
=83.4.
=(20-1)÷1.9,
=19÷1.9,
=10;
(2)(
5 |
6 |
1 |
2 |
2 |
3 |
=
5 |
6 |
1 |
2 |
2 |
3 |
=20+12-16,
=16;
(3)378-26-74,
=378-(26+74),
=378-100,
=278;
(4)1.25×32×25,
=1.25×8×4×25,
=(1.25×8)×(4×25),
=10×100,
=1000;
(5)1+0.45÷0.9-
7 |
8 |
=1+0.5-0.875,
=1.5-0.875,
=0.625;
(6)8.34×17-7×8.34,
=8.34×(17-7),
=8.34×10,
=83.4.
点评:本题考查了四则混合运算的计算法则,同时注意运用恰当的方法或定律进行简算.
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