问题 解答题
下列各题怎样算简便就怎样算.
1
7
9
÷8×11
1
4
×(3-1
2
5
7
9
÷
11
5
+
2
9
×
5
11
88-7.5+12-42
1
2
4
4
5
-(2
4
5
+
5
12
答案

(1)1

7
9
÷8×11
1
4
×(3-1
2
5
),

=1

7
9
÷8×11
1
4
×1
3
5

=(

16
9
×
1
8
)×(
45
4
×
8
5
),

=

2
9
×18,

=4;

(2)

7
9
÷
11
5
+
2
9
×
5
11

=

7
9
×
5
11
+
2
9
×
5
11

=(

7
9
+
2
9
)×
5
11

=1×

5
11

=

5
11

(3)88-7.5+12-42

1
2

=(88+12)-(7.5+42.5),

=100-50,

=50;

(4)4

4
5
-(2
4
5
+
5
12
),

=4

4
5
-2
4
5
-
5
12

=2-

5
12

=1

7
12

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