题目内容
计算9+
×4+8+
×5+7+
×6+6+
×7+5+
×8+4+
×9.
| 16 |
| 39 |
| 16 |
| 39 |
| 16 |
| 39 |
| 16 |
| 39 |
| 16 |
| 39 |
| 16 |
| 39 |
9+
×4+8+
×5+7+
×6+6+
×7+5+
×8+4+
×9
=(9+8+7+6+5+4)+(
×4+
×5+
×6+
×7+
×8+
×9,
=(9+8+7+6+5+4)+
×(9+8+7+6+5+4),
=(9+8+7+6+5+4)×(1+
),
=39×
,
=55.
| 16 |
| 39 |
| 16 |
| 39 |
| 16 |
| 39 |
| 16 |
| 39 |
| 16 |
| 39 |
| 16 |
| 39 |
=(9+8+7+6+5+4)+(
| 16 |
| 39 |
| 16 |
| 39 |
| 16 |
| 39 |
| 16 |
| 39 |
| 16 |
| 39 |
| 16 |
| 39 |
=(9+8+7+6+5+4)+
| 16 |
| 39 |
=(9+8+7+6+5+4)×(1+
| 16 |
| 39 |
=39×
| 55 |
| 39 |
=55.
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