题目内容
(2011?田东县)用简便方法计算.
4×1.28×25
÷
+
×
.
4×1.28×25
7 |
9 |
11 |
5 |
2 |
9 |
5 |
11 |
分析:(1)运用乘法交换律简算;
(2)先把除法变成乘法,再运用乘法分配律简算.
(2)先把除法变成乘法,再运用乘法分配律简算.
解答:解:(1)4×1.28×25,
=4×25×1.28,
=100×1.28,
=128;
(2)
÷
+
×
,
=
×
+
×
,
=(
+
)×
,
=1×
,
=
.
=4×25×1.28,
=100×1.28,
=128;
(2)
7 |
9 |
11 |
5 |
2 |
9 |
5 |
11 |
=
7 |
9 |
5 |
11 |
2 |
9 |
5 |
11 |
=(
7 |
9 |
2 |
9 |
5 |
11 |
=1×
5 |
11 |
=
5 |
11 |
点评:此题是考查四则混合运算,要仔细观察算式的特点,灵活运用一些定律进行简便计算.
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