问题 解答题
下面各题怎么简便怎么算.
8
9
×(
7
16
-
1
4
)÷
1
2

78÷[32×(1-
5
8
)+144];
7
15
×
4
5
-
2
15
×
4
5

0.32×2.5×0.125.
答案

(1)

8
9
×(
7
16
-
1
4
)÷
1
2

=

8
9
×
3
16
×2,

=

1
3

(2)78÷[32×(1-

5
8
)+144]

=78÷[32×

3
8
+144],

=78÷[12+144],

=78÷156,

=0.5;

(3)

7
15
×
4
5
-
2
15
×
4
5

=(

7
15
-
2
15
)×
4
5

=

1
3
×
4
5

=

4
15

(4)0.32×2.5×0.125

=0.4×0.8×2.5×0.125,

=(0.4×2.5)×(0.8×0.125),

=1×0.1,

=0.1.

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