题目内容
脱式计算,能用简便方法的用简便方法
495÷55+495÷45;
3.3×
+0.75×5
+75%;
×6
;
[16.5×7.2÷
×(12.5%-
)]×
.
495÷55+495÷45;
3.3×
3 |
4 |
7 |
10 |
123454321 |
55555×55555 |
1 |
4 |
[16.5×7.2÷
55 |
7 |
1 |
8 |
15 |
19 |
考点:四则混合运算中的巧算
专题:计算问题(巧算速算)
分析:(1)先算除法,再算加法.
(2)通过数字转化,根据乘法分配律进行简算.
(3)分子分母通过数字转化,把带分数化为假分数,约分计算.
(4)通过数字转化,小括号内的结果为0,因此结果等于0.
(2)通过数字转化,根据乘法分配律进行简算.
(3)分子分母通过数字转化,把带分数化为假分数,约分计算.
(4)通过数字转化,小括号内的结果为0,因此结果等于0.
解答:
解:(1)495÷55+495÷45
=9+11
=20
(2)3.3×
+0.75×5
+75%
=3.3×0.75+5.7×0.75+0.75
=(3.3+5.7+1)×0.75
=10×0.75
=7.5
(3)
×6
=
×
=
(4)[16.5×7.2÷
×(12.5%-
)]×
=[16.5×7.2×
×(
-
)]×
=[16.5×7.2×
×0]×
=0×
=0
=9+11
=20
(2)3.3×
3 |
4 |
7 |
10 |
=3.3×0.75+5.7×0.75+0.75
=(3.3+5.7+1)×0.75
=10×0.75
=7.5
(3)
123454321 |
55555×55555 |
1 |
4 |
=
11111×11111 |
5×11111×5×11111 |
25 |
4 |
=
1 |
4 |
(4)[16.5×7.2÷
55 |
7 |
1 |
8 |
15 |
19 |
=[16.5×7.2×
7 |
55 |
1 |
8 |
1 |
8 |
15 |
19 |
=[16.5×7.2×
7 |
55 |
15 |
19 |
=0×
15 |
19 |
=0
点评:观察数字特点,灵活运用运算技巧,解决问题.
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