open FILE, "<file.txt";           # Open the file
while( <FILE> ) {                 # read a line
    if ( /(\w+\.csv)/ ) {         # If the line is a filename...
        close $fh if defined $fh; # close previous
        open $fh,">$1";           # and open new for writing
    } elsif ( /([0-9.-]+)/ ) {    # If the line is a number...
        print $fh "$1\n";         # write it
    }
}
close $fh;                        # close the files opened
close FILE;