题目内容
脱式计算.
25÷0.2×(1-
| 15×(
|
| ||||||||||||||||
3÷
|
|
|
考点:整数、分数、小数、百分数四则混合运算,运算定律与简便运算
专题:运算顺序及法则,运算定律及简算
分析:(1)先算小括号里面的,再按顺序将除法转变为乘法计算.
(2)根据乘法分配律将15与括号里的两项相乘,再与17相乘.
(3)先算小括号里面的,再算中括号里面的,最后算除法.
(4)先算除法,再算减法.
(5)25%=0.25,逆用乘法分配律,将0.25放到括号外面,与(
+
)相乘.
(6)先将除法转变为乘法,再用乘法分配律.
(2)根据乘法分配律将15与括号里的两项相乘,再与17相乘.
(3)先算小括号里面的,再算中括号里面的,最后算除法.
(4)先算除法,再算减法.
(5)25%=0.25,逆用乘法分配律,将0.25放到括号外面,与(
7 |
13 |
6 |
13 |
(6)先将除法转变为乘法,再用乘法分配律.
解答:
解:(1)25÷0.2×(1-
)
=25×5×
=100
(2)15×(
+
)×17
=15×
×17+15×
×17
=17+30
=47
(3)
÷[
×(
+
)]
=
÷[
×
]
=
÷
=
(4)3÷
-
÷3
=7-
=6
(5)
×25%+
÷0.25
=
×0.25+
×0.25
=(
+
)×0.25
=1×0.25
=0.25
(6)
×
+
÷
=
×
+
×
=(
+
)×
=2×
=1.25
1 |
5 |
=25×5×
4 |
5 |
=100
(2)15×(
1 |
15 |
2 |
17 |
=15×
1 |
15 |
2 |
17 |
=17+30
=47
(3)
9 |
20 |
1 |
2 |
2 |
3 |
4 |
5 |
=
9 |
20 |
1 |
2 |
22 |
15 |
=
9 |
20 |
11 |
15 |
=
27 |
44 |
(4)3÷
3 |
7 |
3 |
7 |
=7-
1 |
7 |
=6
6 |
7 |
(5)
7 |
13 |
6 |
13 |
=
7 |
13 |
6 |
13 |
=(
7 |
13 |
6 |
13 |
=1×0.25
=0.25
(6)
7 |
4 |
5 |
8 |
1 |
4 |
8 |
5 |
=
7 |
4 |
5 |
8 |
1 |
4 |
5 |
8 |
=(
7 |
4 |
1 |
4 |
5 |
8 |
=2×
5 |
8 |
=1.25
点评:本题考查四则混合运算的运算顺序,以及简便算法的应用.
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