题目内容
神机妙算(写出简算过程) 2005×
| (
| 999
|
(1)2005×
,
=(2004+1)×
,
=2004×
+1×
,
=2003+
,
=2003
;
(2)(
+
)×5×7,
=
×5×7+
×5×7,
=7+10,
=17;
(3)999
+99
+9
+
,
=(999+99+9)+
×3+
,
=[(1000-1)+(100-1)+(10-1)]+(
+
),
=1110-3+3,
=1110.
2003 |
2004 |
=(2004+1)×
2003 |
2004 |
=2004×
2003 |
2004 |
2003 |
2004 |
=2003+
2003 |
2004 |
=2003
2003 |
2004 |
(2)(
1 |
5 |
2 |
7 |
=
1 |
5 |
2 |
7 |
=7+10,
=17;
(3)999
8 |
9 |
8 |
9 |
8 |
9 |
1 |
3 |
=(999+99+9)+
8 |
9 |
1 |
3 |
=[(1000-1)+(100-1)+(10-1)]+(
8 |
3 |
1 |
3 |
=1110-3+3,
=1110.
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