题目内容
计算下面各题,能简算的要简算.
1+0.45÷
|
| 12×(
| ||||||||||||||||||
78×
|
| 〔
|
考点:整数、分数、小数、百分数四则混合运算
专题:运算顺序及法则
分析:(1)把小数化为分数,先算除法,然后从左往右依次运算.
(2)先算括号内的,然后从左往右依次运算.
(3)运用乘法分配律简算.
(4)把百分数和小数化为分数,运用乘法分配律简算.
(5)通过数据转化,运用乘法分配律简算.
(6)把百分数和小数化为分数,先算小括号内的,再算中括号内的,最后算括号外的.
(2)先算括号内的,然后从左往右依次运算.
(3)运用乘法分配律简算.
(4)把百分数和小数化为分数,运用乘法分配律简算.
(5)通过数据转化,运用乘法分配律简算.
(6)把百分数和小数化为分数,先算小括号内的,再算中括号内的,最后算括号外的.
解答:
解:(1)1+0.45÷
-
=1+
×
-
=1+
-
=
(2)
÷(
-
)×
=
÷
×
=
×
×
=
(3)12×(
+
-
)
=12×
+12×
-12×
=3+2-4
=1
(4)78×
+23×25%-0.25
=78×
+23×
-
=(78+23-1)×
=100×
=25
(5)
×8+
×12
=
×5+
×12
=
×(5+12)
=
×17
=8
(6)[
-(0.5+25%)]÷
=[
-(
+
)]÷
=[
-
]÷
=
×
=
9 |
10 |
3 |
4 |
=1+
9 |
20 |
10 |
9 |
3 |
4 |
=1+
1 |
2 |
3 |
4 |
=
3 |
4 |
(2)
1 |
3 |
2 |
3 |
2 |
5 |
3 |
5 |
=
1 |
3 |
4 |
15 |
3 |
5 |
=
1 |
3 |
15 |
4 |
3 |
5 |
=
3 |
4 |
(3)12×(
1 |
4 |
1 |
6 |
1 |
3 |
=12×
1 |
4 |
1 |
6 |
1 |
3 |
=3+2-4
=1
(4)78×
1 |
4 |
=78×
1 |
4 |
1 |
4 |
1 |
4 |
=(78+23-1)×
1 |
4 |
=100×
1 |
4 |
=25
(5)
5 |
17 |
8 |
17 |
=
8 |
17 |
8 |
17 |
=
8 |
17 |
=
8 |
17 |
=8
(6)[
7 |
8 |
9 |
16 |
=[
7 |
8 |
1 |
2 |
1 |
4 |
9 |
16 |
=[
7 |
8 |
3 |
4 |
9 |
16 |
=
1 |
8 |
16 |
9 |
=
2 |
9 |
点评:此题考查了分数的四则混合运算,注意运算顺序和运算法则,灵活运用所学的运算定律简便计算.
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