题目内容
脱式计算,能简算的就简算.
÷[
-(
-
)]
38
-15.38+61.25-4.62
×5.65+3.35×
+
125×83-25×15.
7 |
12 |
3 |
4 |
11 |
20 |
1 |
2 |
38
3 |
4 |
1 |
8 |
1 |
8 |
1 |
8 |
125×83-25×15.
分析:(1)先算小括号里面的减法,再算中括号里面的减法,最后算除法;
(2)根据加法交换律和结合律进行计算;
(3)根据乘法分配律进行计算;
(4)根据乘法分配律进行计算.
(2)根据加法交换律和结合律进行计算;
(3)根据乘法分配律进行计算;
(4)根据乘法分配律进行计算.
解答:解:(1)
÷[
-(
-
)],
=
÷[
-
],
=
÷
,
=
;
(2)38
-15.38+61.25-4.62,
=(38
+61.25)-(15.38+4.62),
=100-20,
=80;
(3)
×5.65+3.35×
+
,
=
×(5.65+3.35+1),
=
×10,
=
;
(4)125×83-25×15,
=(25×5)×83-25×15,
=25×415-25×15,
=25×(415-15),
=25×400,
=10000.
7 |
12 |
3 |
4 |
11 |
20 |
1 |
2 |
=
7 |
12 |
3 |
4 |
1 |
20 |
=
7 |
12 |
7 |
10 |
=
5 |
6 |
(2)38
3 |
4 |
=(38
3 |
4 |
=100-20,
=80;
(3)
1 |
8 |
1 |
8 |
1 |
8 |
=
1 |
8 |
=
1 |
8 |
=
5 |
4 |
(4)125×83-25×15,
=(25×5)×83-25×15,
=25×415-25×15,
=25×(415-15),
=25×400,
=10000.
点评:此题主要考查分数、整数、小数的四则混合运算的运算顺序和应用运算定律进行简便计算.

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