题目内容
计算下面各题,能简算的要简算.
|
|
(
|
分析:(1)运用乘法结合律简算;
(2)(3)运用乘法分配律简算.
(2)(3)运用乘法分配律简算.
解答:解:(1)
×5×
,
=
×(5×
),
=
×
,
=
;
(2)
×
+
×
,
=
×(
+
),
=
×1,
=
;
(3)(
+
+
)×12,
=
×12+
×12+
×12,
=6+4+2,
=12.
| 10 |
| 3 |
| 1 |
| 15 |
=
| 10 |
| 3 |
| 1 |
| 15 |
=
| 10 |
| 3 |
| 1 |
| 3 |
=
| 10 |
| 9 |
(2)
| 5 |
| 6 |
| 5 |
| 13 |
| 5 |
| 6 |
| 8 |
| 13 |
=
| 5 |
| 6 |
| 5 |
| 13 |
| 8 |
| 13 |
=
| 5 |
| 6 |
=
| 5 |
| 6 |
(3)(
| 1 |
| 2 |
| 1 |
| 3 |
| 1 |
| 6 |
=
| 1 |
| 2 |
| 1 |
| 3 |
| 1 |
| 6 |
=6+4+2,
=12.
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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