题目内容

(2013?广州模拟)计算下列各题,能简便的要简便
(1)4×
3
7
+3×
5
9
-5×
3
7
+1×
4
9
+1×
4
7

(2)2008×
2006
2007

(3)2-
6
13
÷
9
26
-
2
3

(4)0.25×1.25×320
(5)0.6×47+52×
3
5
+0.6
(6)9.75+99.75+999.75+9999.75.
分析:(1)分成两组简便计算;
(2)(5)根据乘法分配律简便计算;
(3)先算除法,再根据连减的简算方法计算即可;
(4)变形为0.25×1.25×(4×80),再根据乘法的交换律和结合律简便计算;
(6)变形为10-0.25+100-0.25+1000-0.25+10000-0.25,依此简便计算.
解答:解:(1)4×
3
7
+3×
5
9
-5×
3
7
+1×
4
9
+1×
4
7

=1×
4
7
+4×
3
7
-5×
3
7
+3×
5
9
+1×
4
9

=
4
7
-(5-4)×
3
7
+
15
9
+
4
9

=
4
7
-
3
7
+2
1
9

=
1
7
+2
1
9

=2
16
63


(2)2008×
2006
2007

=(2007+1)×
2006
2007

=2007×
2006
2007
+
2006
2007

=2006+
2006
2007

=2006
2006
2007


(3)2-
6
13
÷
9
26
-
2
3

=2-
4
3
-
2
3

=2-(
4
3
+
2
3

=2-2
=0;

(4)0.25×1.25×320
=0.25×1.25×(4×80)
=(0.25×4)×(1.25×80)
=1×100
=100;

(5)0.6×47+52×
3
5
+0.6
=0.6×(47+52+1)
=0.6×100
=60;

(6)9.75+99.75+999.75+9999.75
=10-0.25+100-0.25+1000-0.25+10000-0.25
=10+100+1000+10000-0.25×4
=11110-1
=11109.
点评:本题考查了四则混合运算的顺序及运算定律的运用.
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