The document discusses how to tackle practical problems involving continuous stirred-tank reactors (CSTRs). It addresses two common questions: 1) Given known reaction rate data and space time for each reactor in a series, how to calculate the exit concentration from the last reactor. 2) Given a required conversion, how to design a suitable reactor system using the minimum space. The document suggests answering the first question by using the known parameters in material balance equations. For the second question, it recommends designing different reactor configurations and sizes and selecting the one requiring minimum space to achieve the specified conversion.