题目内容
递等式计算(能简便的要写出简便过程).
(1)0.8+4
+
+5
;
(2)2.05-0.81÷2.7×4.5;
(3)10.625×2005+2005×
-2005;
(4)
÷(1
-
×
)+
;
(5)8
÷[4.6+1
×(4
-1.15)];
(6)9.8-(
+2.4×2
).
(1)0.8+4
4 |
9 |
1 |
5 |
5 |
9 |
(2)2.05-0.81÷2.7×4.5;
(3)10.625×2005+2005×
3 |
8 |
(4)
4 |
15 |
4 |
5 |
2 |
3 |
5 |
6 |
5 |
6 |
(5)8
4 |
5 |
7 |
9 |
3 |
4 |
(6)9.8-(
3 |
5 |
2 |
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,小数四则混合运算
专题:运算顺序及法则,运算定律及简算
分析:(1)根据加法交换律和加法结合律简算;
(2)先算除法,再算乘法,最后算减法;
(3)运用乘法分配律简算;
(4)先算小括号里面的乘法,再算小括号里面的减法,然后算括号外的除法,最后算括号外的加法;
(5)先算小括号里面的减法,再算中括号里面的乘法,然后算中括号里面的加法,最后算括号外的除法;
(6)先算小括号里面的乘法,再算小括号里面的加法,最后算括号外的减法.
(2)先算除法,再算乘法,最后算减法;
(3)运用乘法分配律简算;
(4)先算小括号里面的乘法,再算小括号里面的减法,然后算括号外的除法,最后算括号外的加法;
(5)先算小括号里面的减法,再算中括号里面的乘法,然后算中括号里面的加法,最后算括号外的除法;
(6)先算小括号里面的乘法,再算小括号里面的加法,最后算括号外的减法.
解答:
解:(1)0.8+4
+
+5
=(0.8+
)+(4
+5
)
=1+10
=11;
(2)2.05-0.81÷2.7×4.5
=2.05-0.3×4.5
=2.05-1.35
=0.7;
(3)10.625×2005+2005×
-2005
=2005×(10.625+
-1)
=2005×10
=20050;
(4)
÷(1
-
×
)+
=
÷(1
-
)+
=
×
+
=
+
=
;
(5)8
÷[4.6+1
×(4
-1.15)]
=8
÷[4.6+1
×3.6]
=8
÷[4.6+6.4]
=8.8÷11
=0.8;
(6)9.8-(
+2.4×2
)
=9.8-(
+2.4×2
)
=9.8-(0.6+6.4)
=9.8-7
=2.8.
4 |
9 |
1 |
5 |
5 |
9 |
=(0.8+
1 |
5 |
4 |
9 |
5 |
9 |
=1+10
=11;
(2)2.05-0.81÷2.7×4.5
=2.05-0.3×4.5
=2.05-1.35
=0.7;
(3)10.625×2005+2005×
3 |
8 |
=2005×(10.625+
2 |
8 |
=2005×10
=20050;
(4)
4 |
15 |
4 |
5 |
2 |
3 |
5 |
6 |
5 |
6 |
=
4 |
15 |
4 |
5 |
5 |
9 |
5 |
6 |
=
4 |
15 |
45 |
24 |
5 |
6 |
=
1 |
2 |
5 |
6 |
=
4 |
3 |
(5)8
4 |
5 |
7 |
9 |
3 |
4 |
=8
4 |
5 |
7 |
9 |
=8
4 |
5 |
=8.8÷11
=0.8;
(6)9.8-(
3 |
5 |
2 |
3 |
=9.8-(
3 |
5 |
2 |
3 |
=9.8-(0.6+6.4)
=9.8-7
=2.8.
点评:本题考查了四则混合运算,注意运算顺序和运算法则,灵活运用所学的运算定律进行简便计算.
![](http://thumb2018.1010pic.com/images/loading.gif)
练习册系列答案
相关题目