What year is your Belgium gun from here are the numbers from it 98750?
You are asking a question that has almost zero possiblity of
being answered. You have not provided any information beyond the
serial number. This is equivalent to walking into a car dealer and
saying "I have car, what is it worth?". If you can provide the name
of the maker (Belgium has many gun makers), caliber/gauge, type of
action, type of weapon ( hand gun or long gun) and a detailed
description of finish, features, wood used in the stock,
accessories, any engraving and if origianal paper work is present,
someone might be able to help.