题目内容
能简算的要简算.
13
|
18
|
|
13
|
分析:(1)根据加法结合律和减法的性质简算;
(2)先把18
分解成18+
,再把除法变成乘法,再运用乘法分配律简算;
(3)同时运算乘法和除法,最后算加法;
(4)先把除法变成乘法,再运用乘法分配律简算.
(2)先把18
9 |
10 |
9 |
10 |
(3)同时运算乘法和除法,最后算加法;
(4)先把除法变成乘法,再运用乘法分配律简算.
解答:解:(1)13
-3
-2
+2
,
=(13
+2
)-(3
+2
),
=16-6,
=10;
(2)18
÷9,
=(18+
)×
,
=18×
+
×
,
=2+
,
=2
;
(3)
×2
+2
÷1
,
=
×
+
×
,
=
+
,
=3
;
(4)13
×
+6
÷16,
=13
×
+6
×
,
=(13
+6
)×
,
=20×
,
=1
.
5 |
11 |
4 |
7 |
3 |
7 |
6 |
11 |
=(13
5 |
11 |
6 |
11 |
4 |
7 |
3 |
7 |
=16-6,
=10;
(2)18
9 |
10 |
=(18+
9 |
10 |
1 |
9 |
=18×
1 |
9 |
9 |
10 |
1 |
9 |
=2+
1 |
10 |
=2
1 |
10 |
(3)
5 |
8 |
2 |
3 |
1 |
3 |
1 |
3 |
=
5 |
8 |
8 |
3 |
7 |
3 |
3 |
4 |
=
5 |
3 |
7 |
4 |
=3
5 |
12 |
(4)13
7 |
8 |
1 |
16 |
1 |
8 |
=13
7 |
8 |
1 |
16 |
1 |
8 |
1 |
16 |
=(13
7 |
8 |
1 |
8 |
1 |
16 |
=20×
1 |
16 |
=1
1 |
4 |
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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