题目内容
(2010?常熟市)
脱式计算,能简算的要简算. ①11.2-0.32+2.8-8.68 |
②105×(
|
③360÷15-2.5×1.5 | ||||||||||||
④0.25×3.2×12.5 | ⑤
|
⑥
|
分析:(1)依据加法交换律和减法的性质简算,
(2)运用乘法分配律解答,
(3)依据四则运算计算方法解答,
(4)化3.2=0.4×8,再运用乘法结合律解答,
(5)运用乘法分配律解答,
(6)依据四则运算计算方法解答.
(2)运用乘法分配律解答,
(3)依据四则运算计算方法解答,
(4)化3.2=0.4×8,再运用乘法结合律解答,
(5)运用乘法分配律解答,
(6)依据四则运算计算方法解答.
解答:解:(1)11.2-0.32+2.8-8.68,
=(11.2+2.8)-(0.32+8.68),
=14-9,
=5;
(2)105×(
+
+
),
=105×
+105×
+105×
,
=15+70+21,
=106;
(3)360÷15-2.5×1.5,
=24-3.75,
=20.25;
(4)0.25×3.2×12.5,
=(0.25×0.4)×(8×12.5),
=0.1×100,
=10;
(5)
×
+
÷13,
=
×(
+
),
=
×1,
=
;
(6)
÷[1-(
+
)],
=
÷[1-
],
=
÷
,
=
.
=(11.2+2.8)-(0.32+8.68),
=14-9,
=5;
(2)105×(
1 |
7 |
2 |
3 |
1 |
5 |
=105×
1 |
7 |
2 |
3 |
1 |
5 |
=15+70+21,
=106;
(3)360÷15-2.5×1.5,
=24-3.75,
=20.25;
(4)0.25×3.2×12.5,
=(0.25×0.4)×(8×12.5),
=0.1×100,
=10;
(5)
7 |
8 |
12 |
13 |
7 |
8 |
=
7 |
8 |
12 |
13 |
1 |
13 |
=
7 |
8 |
=
7 |
8 |
(6)
2 |
15 |
1 |
5 |
1 |
3 |
=
2 |
15 |
8 |
15 |
=
2 |
15 |
7 |
15 |
=
2 |
7 |
点评:本题主要考查学生对于四则混合运算以及根据数据的特点简算的能力.
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