We investigate benefits and catches of math problem databases with MathML functionalities based on our case studies in our math classes. We conducted online quizes in the classes of Calculus in 2006-2008 using our system of math problem database (we call this QDB). The result was exactly what we expected, namely, we could develop the system in a short period of time and the students could get the evaluation of the quiz immediately after they finished and submitted the quiz. Also, we made a midterm exam of Calculus and showed the answer on the web using our system. From these experiences, we found that QDB is ideal for some purposes, but also noticed that the environments for MathML are not sufficient yet, and that improvements of QDB can be done but only in a limited form. We think that we can make QDB more useful by adding functionalities even if they are for a rather narrow range of purposes and that the simplicity of the system should be maintained in order for the system to be usermaintainable.