题目内容
用自己喜欢的方法计算,□中填入适当的数后使计算简便.
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分析:(1)按照从左到右的顺序计算;
(2)先算小括号里面的加法,再算括号外的除法,最后算乘法;
(3)(4)都运用乘法分配律简算,根据乘法分配律在方框里面填上合适的数.
(2)先算小括号里面的加法,再算括号外的除法,最后算乘法;
(3)(4)都运用乘法分配律简算,根据乘法分配律在方框里面填上合适的数.
解答:解:(1)
÷
×
,
=
×
,
=
;
(2)
÷(
+
)×
,
=
÷
×
,
=
×
,
=
;
(3)
×
+□×
要使本题计算简便,□中应填
;
×
+
×
,
=(
+
)×
,
=1×
,
=
;
(4)
×
+
÷□要使本题计算简便,□应填17.
×
+
÷17,
=
×
+
×
,
=(
+
)×
,
=1×
,
=
.
5 |
8 |
3 |
4 |
9 |
25 |
=
5 |
6 |
9 |
25 |
=
3 |
10 |
(2)
4 |
9 |
1 |
3 |
1 |
6 |
3 |
4 |
=
4 |
9 |
1 |
2 |
3 |
4 |
=
8 |
9 |
3 |
4 |
=
2 |
3 |
(3)
2 |
7 |
8 |
13 |
8 |
13 |
5 |
7 |
2 |
7 |
8 |
13 |
5 |
7 |
8 |
13 |
=(
2 |
7 |
5 |
7 |
8 |
13 |
=1×
8 |
13 |
=
8 |
13 |
(4)
5 |
6 |
1 |
17 |
1 |
6 |
5 |
6 |
1 |
17 |
1 |
6 |
=
5 |
6 |
1 |
17 |
1 |
6 |
1 |
17 |
=(
5 |
6 |
1 |
6 |
1 |
17 |
=1×
1 |
17 |
=
1 |
17 |
点评:本题考查了四则混合运算,注意运算顺序和运算法则,灵活运用所学的运算定律进行简便计算.
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