题目内容

8
17
÷23+
1
23
×
9
17
+
1
23

[5-(11.9-8.4)×1
1
3
]÷130%
3
7
20
÷[5
3
4
-4.5×(20%+
1
3
)]
2222×
27
100
+6666×0.09-3333×0.16.
分析:(1)把除法改为乘法,运用乘法分配律的逆运算简算;
(2)先算小括号内的,再算中括号内的乘法,然后算中括号内的减法,最后算括号外的除法;
(3)先算下括号内的,再算中括号内的乘法,然后算中括号内的减法,最后算括号外的除法;
(4)根据数字特点,把原式变为1111×2×0.27+1111×6×0.09-1111×3×0.16,运用乘法分配律的逆运算简算.
解答:解:(1)
8
17
÷23+
1
23
×
9
17
+
1
23

=
8
17
×
1
23
+
1
23
×
9
17
+
1
23

=(
8
17
+
9
17
+1)×
1
23

=2×
1
23

=
2
23


(2)[5-(11.9-8.4)×1
1
3
]÷130%,
=[5-3.5×
4
3
]÷130%,
=[5-
7
2
×
4
3
]÷130%,
=[5-
14
3
13
10

=
1
3
×
10
13

=
10
39


(3)3
7
20
÷[5
3
4
-4.5×(20%+
1
3
)],
=3
7
20
÷[5
3
4
-4.5×(
1
5
+
1
3
)],
=3
7
20
÷[5
3
4
-4.5×
8
15
],
=3
7
20
÷[5
3
4
-
12
5
],
=
67
20
÷
67
20

=1;

(4)2222×
27
100
+6666×0.09-3333×0.16,
=1111×2×0.27+1111×6×0.09-1111×3×0.16,
=1111×(0.54+0.54-0.48),
=1111×0.6,
=666.6.
点评: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简便计算.
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