题目内容
下面各题,怎样简做简便怎样算.
| 20.7-6.32-3.68 | 0.671×5.2+6.71×0.48 | ||||||||||||||||||||||
|
|
|
考点:分数的四则混合运算
专题:运算顺序及法则
分析:(1)运用乘法分配律简算;
(2)根据减法的性质简算;
(3)根据乘法分配律简算;
(4)先算小括号里面的加法,再算括号外的除法;
(5)先同时运算除法和乘法,再算减法;
(6)先算小括号里面的减法,再算中括号里面的减法,再算括号外的乘法.
(2)根据减法的性质简算;
(3)根据乘法分配律简算;
(4)先算小括号里面的加法,再算括号外的除法;
(5)先同时运算除法和乘法,再算减法;
(6)先算小括号里面的减法,再算中括号里面的减法,再算括号外的乘法.
解答:
解:(1)
×
+0.25×
+
=
×(
+
+1)
=
×2
=
;
(2)20.7-6.32-3.68
=20.7-(6.32+3.68)
=20.7-10
=10.7;
(3)0.671×5.2+6.71×0.48
=0.671×5.2+0.671×4.8
=0.671×(5.2+4.8)
=0.671×10
=6.71;
(4)
÷(
+
)
=
÷
=
;
(5)
÷
-
×
=
-
=
;
(6)
×[
-(
-
)]
=
×[
-
]
=
×
=
.
1 |
4 |
5 |
7 |
2 |
7 |
1 |
4 |
=
1 |
4 |
5 |
7 |
2 |
7 |
=
1 |
4 |
=
1 |
2 |
(2)20.7-6.32-3.68
=20.7-(6.32+3.68)
=20.7-10
=10.7;
(3)0.671×5.2+6.71×0.48
=0.671×5.2+0.671×4.8
=0.671×(5.2+4.8)
=0.671×10
=6.71;
(4)
9 |
16 |
3 |
8 |
1 |
16 |
=
9 |
16 |
7 |
16 |
=
9 |
7 |
(5)
8 |
15 |
8 |
25 |
5 |
7 |
21 |
50 |
=
5 |
3 |
3 |
10 |
=
41 |
30 |
(6)
8 |
9 |
3 |
4 |
7 |
16 |
1 |
4 |
=
8 |
9 |
3 |
4 |
3 |
16 |
=
8 |
9 |
9 |
16 |
=
1 |
2 |
点评:此题是考查四则混合运算,要仔细观察算式的特点,灵活运用一些定律进行简便计算.
练习册系列答案
相关题目