Eh, if you go that way, it could be made much more efficient. No need for the s/// - you're matching any + already: 
my $output = "";
while ($text =~ m{\G(?:&plus;|(<maths>.*?<\/maths>|[^&<]+|.))}gs) {
    $output .= $1 || "&thinsp;&plus;&thinsp;";
}
print $output, "\n";

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In reply to Re^5: Regular Expression Doubt by Anonymous Monk
in thread Regular Expression Doubt by Anonymous Monk

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