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×
-5×
+1×
+1×
(2)2008×
(3)2-
÷
-
(4)0.25×1.25×320
(5)0.6×47+52×
+0.6
(6)9.75+99.75+999.75+9999.75.
(1)4×
3 |
7 |
5 |
9 |
3 |
7 |
4 |
9 |
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 |
(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.
(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×
-5×
+1×
+1×
=1×
+4×
-5×
+3×
+1×
=
-(5-4)×
+
+
=
-
+2
=
+2
=2
;
(2)2008×
=(2007+1)×
=2007×
+
=2006+
=2006
;
(3)2-
÷
-
=2-
-
=2-(
+
)
=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×
+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.
3 |
7 |
5 |
9 |
3 |
7 |
4 |
9 |
4 |
7 |
=1×
4 |
7 |
3 |
7 |
3 |
7 |
5 |
9 |
4 |
9 |
=
4 |
7 |
3 |
7 |
15 |
9 |
4 |
9 |
=
4 |
7 |
3 |
7 |
1 |
9 |
=
1 |
7 |
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×(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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