题目内容

用你喜欢的方法计算下面各题
8
5
×10×
1
8
=
 25×(
20
17
×
17
40
)-12=
15×
6
5
×
1
6
=
4
5
+
11
10
-
3
25
)×25=
3
4
+
5
8
)×32=
5
9
×
3
4
+
5
9
×
1
4
=
5
4
×
1
8
×16
=
 
1
5
+
2
9
×
3
10
=
44-72×
5
12
=
分析:(1)(3)按照从左到右的顺序计算;
(2)先算小括号里面的乘法,再算括号外的乘法,最后算括号外的减法;
(4)(5)(6)运用乘法分配律简算;
(7)运用乘法交换律简算;
(8)先算乘法,再算加法;
(9)先算乘法,再算加法.
解答:解:(1)
8
5
×10×
1
8

=16×
1
8

=2;

(2)25×(
20
17
×
17
40
)-12
=25×
1
2
-12
=12
1
2
-12
=
1
2


(3)15×
6
5
×
1
6

=18×
1
6

=3;

(4)(
4
5
+
11
10
-
3
25
)×25
=
4
5
×25+
1
10
×25-
3
25
×25
=20-
5
2
-3
=14
1
2


(5)(
3
4
+
5
8
)×32
=32×
3
4
+32×
5
8

=24+20
=44;

(6)
5
9
×
3
4
+
5
9
×
1
4

=
5
9
×(
3
4
+
1
4

=
5
9
×1
=
5
9


(7)
5
4
×
1
8
×16
=
5
4
×16×
1
8

=20×
1
8

=
5
2


(8)
1
5
+
2
9
×
3
10

=
1
5
+
1
15

=
4
15


(9)44-72×
5
12

=44-30
=14.
点评:本题考查了四则混合运算,注意运算顺序和运算法则,灵活运用所学的运算定律进行简便计算.
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