题目内容
(1
+3
+9
)÷(1
+3
+9
).
| 5 |
| 99 |
| 5 |
| 33 |
| 5 |
| 11 |
| 1 |
| 99 |
| 1 |
| 33 |
| 1 |
| 11 |
分析:通过观察,两个括号内的分数很有特点,分母相同.我们先把每个分数化成假分数,变为(
+
+
)÷(
+
+
),于是把104和100分别拿出来,剩下的分数和相同,通过约分,计算得出.
| 104 |
| 99 |
| 104 |
| 33 |
| 104 |
| 11 |
| 100 |
| 99 |
| 100 |
| 33 |
| 100 |
| 11 |
解答:解:(1
+3
+9
)÷(1
+3
+9
),
=(
+
+
)÷(
+
+
),
=(
+
+
)×104÷[(
+
+
)×100],
=104÷100,
=1.04.
| 5 |
| 99 |
| 5 |
| 33 |
| 5 |
| 11 |
| 1 |
| 99 |
| 1 |
| 33 |
| 1 |
| 11 |
=(
| 104 |
| 99 |
| 104 |
| 33 |
| 104 |
| 11 |
| 100 |
| 99 |
| 100 |
| 33 |
| 100 |
| 11 |
=(
| 1 |
| 99 |
| 1 |
| 33 |
| 1 |
| 11 |
| 1 |
| 99 |
| 1 |
| 33 |
| 1 |
| 11 |
=104÷100,
=1.04.
点评:此题属于分数的巧算,在计算前应注意仔细观察,找出数字之间的联系,从而较好地解答问题.
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