题目内容
(2008?高邮市模拟)计算下面各题(可简便计算的应简便计算).
(1)3.87+1.44-0.87+0.56
(2)58.8÷2.1-1.6×3.5
(3)(
+
)×21
(4)5.16×8.5+1.5×5.16
(5)
×(
+
)÷
(6)
×[
÷(
-
)].
(1)3.87+1.44-0.87+0.56
(2)58.8÷2.1-1.6×3.5
(3)(
3 |
7 |
1 |
3 |
(4)5.16×8.5+1.5×5.16
(5)
3 |
10 |
1 |
2 |
1 |
3 |
1 |
8 |
(6)
3 |
8 |
8 |
9 |
5 |
6 |
3 |
4 |
分析:算式(1)可根据加法交换律及结合律进行计算;
算式(3)、(4)可根据乘法分配律进行计算;
算式(2)、(5)、(6)按照四则混合运算的运算顺序计算即可:先算乘除,再算加减,有括号的要先算括号里面的.
算式(3)、(4)可根据乘法分配律进行计算;
算式(2)、(5)、(6)按照四则混合运算的运算顺序计算即可:先算乘除,再算加减,有括号的要先算括号里面的.
解答:解:(1)3.87+1.44-0.87+0.56
=(3.87-0.87)+(1.44+0.56),
=3+2,
=5;
(2)58.8÷2.1-1.6×3.5
=28-5.6,
=22.4;
(3)(
+
)×21
=
×21+
×21,
=9+7,
=16;
(4)5.16×8.5+1.5×5.16
=(8.5+1.5)×5.16,
=10×5.16,
=51.6;
(5)
×(
+
)÷
=
×(
+
)×8,
=
×
×8,
=2;
(6)
×[
÷(
-
)]
=
×[
÷(
-
)],
=
×
×12,
=4.
=(3.87-0.87)+(1.44+0.56),
=3+2,
=5;
(2)58.8÷2.1-1.6×3.5
=28-5.6,
=22.4;
(3)(
3 |
7 |
1 |
3 |
=
3 |
7 |
1 |
3 |
=9+7,
=16;
(4)5.16×8.5+1.5×5.16
=(8.5+1.5)×5.16,
=10×5.16,
=51.6;
(5)
3 |
10 |
1 |
2 |
1 |
3 |
1 |
8 |
=
3 |
10 |
3 |
6 |
2 |
6 |
=
3 |
10 |
5 |
6 |
=2;
(6)
3 |
8 |
8 |
9 |
5 |
6 |
3 |
4 |
=
3 |
8 |
8 |
9 |
10 |
12 |
9 |
12 |
=
3 |
8 |
8 |
9 |
=4.
点评:完成此类题目要认真分析式中数据的特点及内在联系,然后选择合适的方法进行计算.
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