题目内容
(2011?许昌)
用简便方法计算下面各题. 0.25×125%×32 |
14.28-(9.34-5.72) | ||||||||||||
|
|
分析:(1)0.25×125%×32,把百分数化成小数,同时把32 分解为:8×4,然后再运用乘法交换律和结合律进行简算;
(2)14.28-(9.34-5.72),根据减法的运算性质进行简算;
(3)
-
+
-
,根据减法的运算性质进行简算;
(4)
×5.7+3.3÷
.把除数转化为乘它的倒数,再运用乘法分配律进行简算.
(2)14.28-(9.34-5.72),根据减法的运算性质进行简算;
(3)
7 |
8 |
1 |
17 |
9 |
8 |
16 |
17 |
(4)
7 |
15 |
15 |
7 |
解答:解:(1)0.25×125%×32,
=0.25×1.25×8×4,
=(0.25×4)×(1.25×8),
=1×10,
=10;
(2)14.28-(9.34-5.72),
=14.28+5.72-9.34,
=20-9.34,
=10.66;
(3)
-
+
-
,
=
+
-(
+
),
=2-1,
=1;
(4)
×5.7+3.3÷
.
=
×5.7+3.3×
,
=
×(5.7+3.3),
=
×9,
=
,
=4
.
=0.25×1.25×8×4,
=(0.25×4)×(1.25×8),
=1×10,
=10;
(2)14.28-(9.34-5.72),
=14.28+5.72-9.34,
=20-9.34,
=10.66;
(3)
7 |
8 |
1 |
17 |
9 |
8 |
16 |
17 |
=
7 |
8 |
9 |
8 |
1 |
17 |
16 |
17 |
=2-1,
=1;
(4)
7 |
15 |
15 |
7 |
=
7 |
15 |
7 |
15 |
=
7 |
15 |
=
7 |
15 |
=
21 |
5 |
=4
1 |
5 |
点评:此题考查的目的理解掌握乘法交换律、结合律、分配律的意义,以及减法的运算性质,并且能够运用这些运算定律和运算性质对小数、分数四则混合运算进行简便计算.
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