题目内容
脱式计算. 18×
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分析:(1)先把后面两个数相乘,再与第一个数约分,即可解答;
(2)先除以分数,等于乘这个分数的倒数,把除法写成乘法,再进行约分即可解答;
(3)按照运算顺序,先算括号里面的,再利用分数乘法的法则计算即可;
(4)利用乘法的交换律和交换律,先计算
×11和
×13,再把所得的积相乘即可;
(5)(6)直接利用乘法分配律进行简便计算即可.
(2)先除以分数,等于乘这个分数的倒数,把除法写成乘法,再进行约分即可解答;
(3)按照运算顺序,先算括号里面的,再利用分数乘法的法则计算即可;
(4)利用乘法的交换律和交换律,先计算
10 |
11 |
1 |
13 |
(5)(6)直接利用乘法分配律进行简便计算即可.
解答:解:(1)18×
×
,
=18×(
×
),
=18×
,
=10;
(2)
÷
×
,
=
×
×
,
=
;
(3)
×(1÷
),
=
×(1×
),
=
×
,
=2;
(4)
×
×13×11,
=
×11×
×13,
=10×1,
=10;
(5)(
+
)×
,
=
×
+
×
,
=
+1,
=3
;
(6)
×21+28×
,
=
×(21+28),
=
×49,
=13.
5 |
6 |
2 |
3 |
=18×(
5 |
6 |
2 |
3 |
=18×
10 |
18 |
=10;
(2)
3 |
4 |
5 |
28 |
1 |
21 |
=
3 |
4 |
28 |
5 |
1 |
21 |
=
1 |
5 |
(3)
4 |
7 |
2 |
7 |
=
4 |
7 |
7 |
2 |
=
4 |
7 |
7 |
2 |
=2;
(4)
10 |
11 |
1 |
13 |
=
10 |
11 |
1 |
13 |
=10×1,
=10;
(5)(
4 |
5 |
3 |
10 |
10 |
3 |
=
4 |
5 |
10 |
3 |
3 |
10 |
10 |
3 |
=
8 |
3 |
=3
2 |
3 |
(6)
13 |
49 |
13 |
49 |
=
13 |
49 |
=
13 |
49 |
=13.
点评:此题主要考查分数乘法的计算法则以及运算定律的灵活应用.

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