题目内容
计算:(
+
)+(
+
+
)+(
+
+
+
)+…+(
+…+
)
| 1 |
| 3 |
| 2 |
| 3 |
| 1 |
| 4 |
| 2 |
| 4 |
| 3 |
| 4 |
| 1 |
| 5 |
| 2 |
| 5 |
| 3 |
| 5 |
| 4 |
| 5 |
| 1 |
| 100 |
| 99 |
| 100 |
考点:分数的巧算
专题:计算问题(巧算速算)
分析:通过观察,可知:
+
=
,
+
+
=
,(
+
+
+
)=
,…,运用高斯求和公式即可得出答案.
| 1 |
| 3 |
| 2 |
| 3 |
| 3-1 |
| 2 |
| 1 |
| 4 |
| 2 |
| 4 |
| 3 |
| 4 |
| 4-1 |
| 2 |
| 1 |
| 5 |
| 2 |
| 5 |
| 3 |
| 5 |
| 4 |
| 5 |
| 5-1 |
| 2 |
解答:
解:(
+
)+(
+
+
)+(
+
+
+
)+…+(
+…+
)
=
+
+
+…+
=
-
×98
=
-49
=2523.5-49
=2474.5
| 1 |
| 3 |
| 2 |
| 3 |
| 1 |
| 4 |
| 2 |
| 4 |
| 3 |
| 4 |
| 1 |
| 5 |
| 2 |
| 5 |
| 3 |
| 5 |
| 4 |
| 5 |
| 1 |
| 100 |
| 99 |
| 100 |
=
| 3-1 |
| 2 |
| 4-1 |
| 2 |
| 5-1 |
| 2 |
| 100-1 |
| 2 |
=
| 3+4+5+…+100 |
| 2 |
| 1 |
| 2 |
=
| (3+100)×98÷2 |
| 2 |
=2523.5-49
=2474.5
点评:此题解答的关键在于仔细观察数据,根据特点,进行灵活处理数据,运用运算技巧巧妙解答.
练习册系列答案
相关题目
| A、字母A的值是2 |
| B、字母B的值是3 |
| C、字母C的值是2 |
| D、字母D的值是0 |
把
米长的绳子截成相等的6份,每份是这段铁丝的( )
| 2 |
| 3 |
A、
| ||
B、
| ||
C、
| ||
D、
|