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
+
+
+…+
,
=
×(1+2+3+4+5+6+7),
=
×28,
=
;
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×
,
=(2008+1)×
,
=2008×
+
,
=41+
,
=41
;
④
+
+
+…+
,
=
+
+
+…+
,
=1-
+
-
+
-
+…-
+
-
,
=1-
,
=
.
| 1 |
| 2008 |
| 2 |
| 2008 |
| 3 |
| 2008 |
| 7 |
| 2008 |
=
| 1 |
| 2008 |
=
| 1 |
| 2008 |
=
| 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 |
④
| 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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