Here is one way: 
use strict;

# look ma! no $_! ;)

while (<DATA>) {
   s/\d\d(\d\d)\.(\d+)/$1$2/;
   print;
}

__DATA__
1996.40637
1996.41064
1996.41199
1996.41467
1996.41882

[download]

UPDATE: ack! i see it now: you want =~, not = for your substitution lines.

Here is my above while loop with the implicit $_: 

while ($_ = <DATA>) {
   $_ =~ s/\d\d(\d\d)\.(\d+)/$1$2/;
   print $_;
}

[download]

UPDATE 2: re japhy
DOH! ;)

jeffa

In reply to (jeffa) Re: substr on $_ by jeffa
in thread substr on $_ by gisrob

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