not sure to have understood your question: anyway you have to very similar statements that probably can be reduced to one

   qr{ \b \d{3,4} \b }xms
[download]

See perlrequick for the quantifiers introduction.

In addiction, if i understand the issue, you can tell the regex to match only if, for example, the numbers are not between href= and what you can consider the rigth end of your URLs.

More strict is your regex more accurate will be results: you have to know (and predict!) where these digits can be candidate for the substitution.

Only you can tell what your data is: you need to find the right regex for your all possible cases. Know your Data is an important rule. If you can post an exmple of a normal line and also one line with the problem, probably you 'l get better answers.

L*