题目内容

用简便方法计算下面各题.
(1)
54
55
×41

(2)2011×
19
2010

(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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