题目内容

计算,能简算的要简算,并写出主要过程.
306÷(201×47-9413)
1
5
÷[(
2
3
+
1
5
1
13
]

3
8
×35+35×
5
8
5
7
           
2007×2009×(
1
2007×2008
+
1
2008×2009
)

53.7×5.3+537×0.37+53.7      
2
1×2
+
2
2×3
+
2
3×4
+…+
2
2008×2009
分析:(1)先算括号内的乘法,再算扩阿红诶的剑法,最后算括号外的除法;
(2)先算小括号内的,再算中括号内的,最后算括号外的;
(3)运用乘法分配律的逆运算简算;
(4)运用乘法分配律简算;
(5)根据数字特点,把原式变为53.7×5.3+53.7×3.7+53.7,运用乘法分配律的逆运算简算;
(6)通过观察,每个分数的分子都是2,于是先把2拿出来,括号内的分数可以拆成两个分数相减的形式,然后通过加减相抵消的方法,得出结果.
解答:解:(1)306÷(201×47-9413),
=306÷(9447-9413),
=306÷34,
=9;

(2)
1
5
÷[(
2
3
+
1
5
)×
1
13
],
=
1
5
÷[
13
15
×
1
13
],
=
1
5
÷
1
15

=
1
5
×15,
=3;

(3)
3
8
×35+35×
5
8

=(
3
8
+
5
8
)×35,
=1×35,
=35;

(4)2007×2009×(
1
2007×2008
+
1
2008×2009
),
=2007×2009×
1
2007×2008
+2007×2009×
1
2008×2009

=
2009
2008
+
2007
2008

=1+
1
2008
+(1-
1
2008
),
=2;

(5)53.7×5.3+537×0.37+53.7,
=53.7×5.3+53.7×3.7+53.7,
=(5.3+3.7+1)×53.7,
=10×53.7,
=537;

(6)
2
1×2
+
2
2×3
+
2
3×4
+…+
2
2008×2009

=2×(
1
1×2
+
1
2×3
+
1
3×4
+…+
1
2008×2009
),
=2×(1-
1
2
+
1
2
-
1
3
+
1
3
-
1
4
+…+
1
2008
-
1
2009

=2×(1-
1
2009

=2×
2008
2009

=
4016
2009
点评:此题考查了四则混合运算的运算顺序,以及运用运算定律或运算技巧简算的能力.
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