题目内容
脱式计算
0.25×0.125×3.2 |
|
0.25×8.9-
| ||||||
(
|
8470-104×65 | (0.27+0.27+0.27+0.27)×25. |
分析:(1)根据乘法交换律和结合律进行计算;
(2)先算减法,再算除法;
(3)根据乘法分配律进行计算;
(4)根据乘法分配律进行计算;
(5)先算乘法,再算减法;
(6)根据乘法结合律进行计算.
(2)先算减法,再算除法;
(3)根据乘法分配律进行计算;
(4)根据乘法分配律进行计算;
(5)先算乘法,再算减法;
(6)根据乘法结合律进行计算.
解答:解:
(1)0.25×0.125×3.2,
=0.25×0.125×(0.4×8),
=(0.25×0.4)×(0.125××8),
=0.1×1,
=0.1;
(2)
÷(
-50%),
=
÷
,
=
;
(3)0.25×8.9-
×7.9,
=0.25×8.9-0.25×7.9,
=0.25×(8.9-7.9),
=0.25×1,
=0.25;
(4)(
-
)×4×9,
=
×4×9-
×4×9,
=4-3,
=1;
(5)8470-104×65,
=8470-6760,
=1710;
(6)(0.27+0.27+0.27+0.27)×25,
=(0.27×4)×25,
=0.27×(4×25),
=0.27×100,
=27.
(1)0.25×0.125×3.2,
=0.25×0.125×(0.4×8),
=(0.25×0.4)×(0.125××8),
=0.1×1,
=0.1;
(2)
13 |
20 |
3 |
4 |
=
13 |
20 |
1 |
2 |
=
13 |
10 |
(3)0.25×8.9-
1 |
4 |
=0.25×8.9-0.25×7.9,
=0.25×(8.9-7.9),
=0.25×1,
=0.25;
(4)(
1 |
9 |
1 |
12 |
=
1 |
9 |
1 |
12 |
=4-3,
=1;
(5)8470-104×65,
=8470-6760,
=1710;
(6)(0.27+0.27+0.27+0.27)×25,
=(0.27×4)×25,
=0.27×(4×25),
=0.27×100,
=27.
点评:四则运算,先弄清运算顺序,然后再进一步计算,能简算的要简算.
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