题目内容
计算:
(1)238÷238
;
(2)(9
+7
)÷(
+
).
(1)238÷238
238 |
239 |
(2)(9
2 |
7 |
2 |
9 |
5 |
7 |
5 |
9 |
考点:分数的巧算
专题:计算问题(巧算速算)
分析:(1)先把带分数化成假分数,分子不必算出来,因为在计算过程中能够月份.
(2)原式变为[16+(
+
)]÷(
+
),运用除法的运算性质计算.
(2)原式变为[16+(
2 |
7 |
2 |
9 |
5 |
7 |
5 |
9 |
解答:
解:(1)238÷238
=238÷
=238×
=
(2)(9
+7
)÷(
+
)
=(9+
+7+
)÷(
+
)
=[16+(
+
)]÷(
+
)
=16÷(
+
)+(
+
)÷(
+
)
=16÷
+
=
+
=13
238 |
239 |
=238÷
238×239+238 |
239 |
=238×
239 |
238×(239+1) |
=
239 |
240 |
(2)(9
2 |
7 |
2 |
9 |
5 |
7 |
5 |
9 |
=(9+
2 |
7 |
2 |
9 |
5 |
7 |
5 |
9 |
=[16+(
2 |
7 |
2 |
9 |
5 |
7 |
5 |
9 |
=16÷(
5 |
7 |
5 |
9 |
2 |
7 |
2 |
9 |
5 |
7 |
5 |
9 |
=16÷
80 |
63 |
2 |
5 |
=
63 |
5 |
2 |
5 |
=13
点评:仔细分析数据,根据数据特点,运用合适的简便方法计算.
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