问题 解答题
3.7×8.8+2.2×3.7-3.7
8
9
×{
3
4
-(
7
16
-0.25)}

1
2
+
1
6
+
1
12
+
1
20
+
1
30
答案

(1)3.7×8.8+2.2×3.7-3.7,

=3.7×(8.8+2.2-1),

=3.7×10,

=37;

(2)

8
9
×{
3
4
-(
7
16
-0.25)},

=

8
9
×(
3
4
+
1
4
-
7
16
),

=

8
9
×(1-
7
16
),

=

8
9
×
9
16

=

1
2

(3)

1
2
+
1
6
+
1
12
+
1
20
+
1
30

=(1-

1
2
)+(
1
2
-
1
3
)+(
1
3
-
1
4
)+(
1
4
-
1
5
)+(
1
5
-
1
6
),

=1-

1
2
+
1
2
-
1
3
+
1
3
+…+
1
5
-
1
6

=1-

1
6

=

5
6

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