问题 解答题
25×1.25×321
8
13
×
13
42
+5
1
5
÷
4
5
5
21
×
3
4
+
3
4
×2
16
21
+
3
4
1
5
÷2.4×
2
3
÷
4
7
5
11
×34×12
1
10
×
2
51
1
1
2
÷(1
1
4
÷1
1
6
)
答案

(1)25×1.25×32,

=25×1.25×(4×8),

=(25×4)×(1.25×8),

=100×10,

=1000;

(2)1

8
13
×
13
42
+5
1
5
÷
4
5

=

1
2
+
13
2

=7;

(3)

5
21
×
3
4
+
3
4
×2
16
21
+
3
4

=(

5
21
+2
16
21
+1)×
3
4

=4×

3
4

=3;

(4)

1
5
÷2.4×
2
3
÷
4
7

=

1
12
×
2
3
÷
4
7

=

1
18
÷
4
7

=

7
72

(5)

5
11
×34×12
1
10
×
2
51

=(

5
11
×12
1
10
)×(34×
2
51
),

=

11
2
×
4
3

=

22
3

(6)1

1
2
÷(1
1
4
÷1
1
6
)

=1

1
2
÷
15
14

=

7
5

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