题目内容

能用简便方法的用简便方法计算.
105×32-3232÷32
125×3
1
3
×0.8×
3
10

(
1
7
-
1
9
)×  63-
2
3
 
210.5×[(6.05-3.35)÷1.5]
(
5
6
-
3
4
2
5
÷
1
2

0.75×16+
3
4
×5-75%
分析:(1)把32看作30+2,根据乘法分配律求出105×(30+2)=3150+210,同时计算出3232÷32=101,然后通过拆项和加法结合律简算;
(2)运用乘法交换律和结合律简算;
(3)运用乘法分配律计算(
1
7
-
1
9
)×63,然后与
2
3
相减即可;
(4)按运算顺序进行计算,先算小括号内的减法,再算中括号内的除法,最后算括号外的乘法;
(5)把除法改为乘法,然后按运算顺序计算,此题应注意约分;
(6)把分数和百分数化为小数,用乘法分配的逆运算简算.
解答:解:(1)105×32-3232÷32,
=3360-101,
=3159;

(2)125×3
1
3
×0.8×
3
10

=125×0.8×(
10
3
×
3
10
),
=100×1,
=100;

(3)(
1
7
-
1
9
)×63-
2
3

=
1
7
×63-
1
9
×63-
2
3

=9-7-
2
3

=2-
2
3

=1
1
3


(4)210.5×[(6.05-3.35)÷1.5],
=210.5×[(6.05-3.35)÷1.5],
=210.5×[2.7÷1.5],
=210.5×1.8,
=378.9;

(5)(
5
6
-
3
4
)×
2
5
÷
1
2

=(
10
12
-
9
12
)×
2
5
×2,
=
1
12
×
2
5
×2,
=
1
15


(6)0.75×16+
3
4
×5-75%

=0.75×16+0.75×5-0.75,
=(16+5-1)×0.75,
=20×0.75,
=15.
点评:此题考查了学生对四则混合运算顺序的掌握,以及运用运算定律简算的能力.
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