问题 解答题
①12345×99+12345×999-12345×98
②1-
1
2
-
1
4
-
1
8
-
1
16
-
1
32
答案

①12345×99+12345×999-12345×98,

=12345×(99+999-98),

=12345×1000,

=12345000;

②1-

1
2
-
1
4
-
1
8
-
1
16
-
1
32

=

1
2
-
1
4
-
1
8
-
1
16
-
1
32

=

1
4
-
1
8
-
1
16
-
1
32

=

1
8
-
1
16
-
1
32

=

1
16
-
1
32

=

1
32

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