Hello,
I can write a small windows application that will allow you to simply type the numbers or load a CSV file (you can create this with Excel or LibreOffice Calc, or simply usea text editor to create the file - a CSV file is a text file where each row is a text line, and each text line has the numbers separated by a simple comma character).
You would then be able to enter several 3 or 4 digit numbers and the application will highlight them for you on the screen.
Such an application can be done in a few hours from the moment you select my proposal.
Marius