题目内容
计算下面各题,怎样算简便就怎样算.
15×
|
30×(
| ||||||||||||||
|
10-(
| ||||||||||||||
(
|
[(
|
分析:②③使用乘法分配律简算;①④⑤⑥按运算顺序和计算法则计算即可.
解答:解:①15×
÷
,
=15×
×
,
=2
;
②30×(
+
-
),
=30×
+30×
-30×
,
=12+5-8,
=9;
③
×
+
×
,
=(
+
)×
,
=1×
,
=
;
④10-(
+
×2),
=10-(
+
),
=10-2,
=8;
⑤(
+
×
) ÷
,
=(
+
)×
,
=
×
,
=
;
⑥[(
-1)÷
] ×
,
=[
×
]×
,
=
×
,
=
.
| 3 |
| 8 |
| 9 |
| 4 |
=15×
| 3 |
| 8 |
| 4 |
| 9 |
=2
| 1 |
| 2 |
②30×(
| 2 |
| 5 |
| 1 |
| 6 |
| 4 |
| 15 |
=30×
| 2 |
| 5 |
| 1 |
| 6 |
| 4 |
| 15 |
=12+5-8,
=9;
③
| 3 |
| 5 |
| 7 |
| 13 |
| 3 |
| 5 |
| 6 |
| 13 |
=(
| 7 |
| 13 |
| 6 |
| 13 |
| 3 |
| 5 |
=1×
| 3 |
| 5 |
=
| 3 |
| 5 |
④10-(
| 4 |
| 3 |
| 1 |
| 3 |
=10-(
| 4 |
| 3 |
| 2 |
| 3 |
=10-2,
=8;
⑤(
| 7 |
| 5 |
| 4 |
| 5 |
| 1 |
| 8 |
| 9 |
| 8 |
=(
| 7 |
| 5 |
| 1 |
| 10 |
| 8 |
| 9 |
=
| 3 |
| 2 |
| 8 |
| 9 |
=
| 4 |
| 3 |
⑥[(
| 7 |
| 5 |
| 3 |
| 5 |
| 5 |
| 4 |
=[
| 2 |
| 5 |
| 5 |
| 3 |
| 5 |
| 4 |
=
| 2 |
| 3 |
| 5 |
| 4 |
=
| 5 |
| 6 |
点评:观察各题,注意使用定律进行简算,同时注意计算时要细心.
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