问题 解答题
用简便方法计算下面各题.
(1)
54
55
×41

(2)2011×
19
2010
答案

(1)

54
55
×41,

=(1-

1
55
)×41,

=1×41-

1
55
×41,

=41-

41
55

=40

14
55

(2)2011×

19
2010

=(2010+1)×

19
2010

=2010×

19
2010
+1×
19
2010

=19+

19
2010

=19

19
2010

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