题目内容

(2007?淮安模拟)下面各题怎样简便就怎样算
14.4÷0.125÷8
1
6
+
1
8
)×24×
1
5
2.34×56-23.4×5.6
1.5×
4
5
+0.8×5.5+2×
4
5
1005÷[42×(
5
6
-
5
7
)]
12
35
÷[1-(
1
5
+
1
7
)].
分析:(1)运用除法的性质简算;
(2)运用乘法分配律简算;
(3)根据数字特点,原式变为2.34×56-2.34×56,运用乘法分配律简算;
(4)把分数化为小数,运用乘法分配律简算;
(5)中括号内运用乘法分配律简算,最后算括号外的除法;
(6)先算小括号内的,再算中括号内的,最后算括号外的.
解答:解:(1)14.4÷0.125÷8,
=14.4÷(0.125×8),
=14.4÷1,
=14.4;

(2)(
1
6
+
1
8
)×24×
1
5

=
1
6
×24×
1
5
+
1
8
×24×
1
5

=
4
5
+
3
5

=
7
5


(3)2.34×56-23.4×5.6,
=2.34×56-2.34×56
=2.34×(56-56),
=0;

(4)1.5×
4
5
+0.8×5.5+2×
4
5

=1.5×0.8+0.8×5.5+2×0.8,
=(1.5+5.5+2)×0.8,
=9×0.8,
=7.2;

(5)1005÷[42×(
5
6
-
5
7
)],
=1005÷[42×
5
6
-42×
5
7
],
=1005÷[35-30],
=1005÷5,
=201;

(6)
12
35
÷[1-(
1
5
+
1
7
)],
=
12
35
÷[1-
12
35
],
=
12
35
÷
24
35

=
12
35
×
35
24

=
1
2
点评:考查了运算定律与简便运算,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律简便计算.
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