题目内容

1
2008
+
2
2008
+
3
2008
+…+
7
2008
=______;
2.008×390+20.08×41+200.8×2=______;
2009×
41
2008
=______;
2
1×3
+
2
3×5
+
2
5×7
+…+
2
97×99
=______.
1
2008
+
2
2008
+
3
2008
+…+
7
2008

=
1
2008
×(1+2+3+4+5+6+7),
=
1
2008
×28,
=
7
502


②2.008×390+20.08×41+200.8×2,
=2.008×390+2.008×410+2.008×200,
=2.008×(390+410+200),
=2.008×1000,
=2008;

③2009×
41
2008

=(2008+1)×
41
2008

=2008×
41
2008
+
41
2008

=41+
41
2008

=41
41
2008


2
1×3
+
2
3×5
+
2
5×7
+…+
2
97×99

=
3-1
1×3
+
5-3
3×5
+
7-5
5×7
+…+
99-97
97×99

=1-
1
3
+
1
3
-
1
5
+
1
5
-
1
7
+…-
1
97
+
1
97
-
1
99

=1-
1
99

=
98
99
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