题目内容

简便计算下面各题.
44×0.25            
1
15
+
2
17
)×15×17           
85.57-(5.57-3.8)
99999×77778+33333×66666        
27×
136
137
+136×
20
137
+180×
68
137
分析:(1)把44看作11×4,运用乘法结合律简算;
(2)根据数字特点,运用乘法分配律简算;
(3)运用减法的性质去括号,再运用加法结合律简算;
(4)把66666看作3×22222,原式变为99999×77778+99999×22222,运用乘法分配律简算;
(5)根据数字特点,把原式变为27×136×
1
137
+136×20×
1
137
+180×68×
1
137
,运用乘法分配律的逆运算简算.
解答:解:(1)44×0.25,
=11×4×0.25,
=11×(4×0.25),
=11×1,
=11;

(2)(
1
15
+
2
17
)×15×17,
=
1
15
×15×17+
2
17
×15×17,
=17+30,
=47;

(3)85.57-(5.57-3.8),
=85.57-5.57+3.8,
=80+3.8,
=83.8;

(4)99999×77778+33333×66666,
=99999×77778+33333×(3×22222),
=99999×77778+99999×22222,
=99999×(77778+22222),
=99999×100000,
=9999900000;

(5)27×
136
137
+136×
20
137
+180×
68
137

=27×136×
1
137
+136×20×
1
137
+180×68×
1
137

=27×136×
1
137
+136×20×
1
137
+90×136×
1
137

=(27+20+90)×136×
1
137

=137×136×
1
137

=136.
点评:完成本题要注意分析式中数据,运用合适的简便方法计算.
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