题目内容
(2011?石家庄模拟)
计算下列各题(能简便计算的要简算) 56×(
|
(
|
分析:(1)根据乘法的分配律作答;
(2)根据连续减去两个数,等于减去这两个数的和;
(3)将3.2拆成0.8和4的积,再根据乘法的交换律作答;
(4)、(5)、(6)根据乘法的分配律作答.
(2)根据连续减去两个数,等于减去这两个数的和;
(3)将3.2拆成0.8和4的积,再根据乘法的交换律作答;
(4)、(5)、(6)根据乘法的分配律作答.
解答:解:(1)56×(
-
),
=56×
-56×
,
=24-21,
=3;
(2)9.75-3.42-5.58,
=9.75-(3.42+5.58),
=9.75-9,
=0.75;
(3)125×0.25×3.2,
=125×0.25×4×0.8,
=125×0.8×0.25×4,
=100×1,
=100;
(4)(
-
)×
,
=
×
-
×
,
=
-
=
-
,
=
;
(5)
×
+
÷8
=
×
+
×
,
=
×(
+
),
=
×
,
=
;
(6)
+
×
,
=
×(3+
),
=
×
,
=
.
3 |
7 |
3 |
8 |
=56×
3 |
7 |
3 |
8 |
=24-21,
=3;
(2)9.75-3.42-5.58,
=9.75-(3.42+5.58),
=9.75-9,
=0.75;
(3)125×0.25×3.2,
=125×0.25×4×0.8,
=125×0.8×0.25×4,
=100×1,
=100;
(4)(
3 |
5 |
1 |
4 |
4 |
7 |
=
3 |
5 |
4 |
7 |
1 |
4 |
4 |
7 |
=
12 |
35 |
1 |
7 |
=
12 |
35 |
5 |
35 |
=
1 |
5 |
(5)
3 |
8 |
6 |
7 |
6 |
7 |
=
3 |
8 |
6 |
7 |
6 |
7 |
1 |
8 |
=
6 |
7 |
3 |
8 |
1 |
8 |
=
6 |
7 |
1 |
2 |
=
3 |
7 |
(6)
3 |
4 |
1 |
4 |
2 |
3 |
=
1 |
4 |
2 |
3 |
=
1 |
4 |
11 |
3 |
=
11 |
12 |
点评:解答此题的关键是,运用乘法的分配律及乘法的交换律,使计算简便.
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