% comment to self: always write your multicols before your enumerates!
 \begin{exercisebox}                                                                                                                  
     \subsection{Exercises:}                                                                                                          
     \begin{doublespace}                                                                                                              
     \begin{questions}                                                                                                                
         \Question[4] Simplify:                                                                                                       
             \begin{multicols}{2}                                                                                                     
                 \begin{parts}                                                                                                        
                 \part \(\sqrt{108}=\fillin[$6\sqrt{3}$]\)                                                                              
                 \part \(\sqrt{90}=\fillin[$3\sqrt{10}$]\)                                                                              
                 \part \(\sqrt{52}=\fillin[$2\sqrt{13}$]\)                                                                              
                 \part \(\sqrt{98}=\fillin[$7\sqrt{2}$]\)                                                                               
                 \end{parts}                                                                                                          
             \end{multicols}                                                                                                          
         \Question[4] Add or Subtract:                                                                                                
             \begin{multicols}{2}                                                                                                     
                 \begin{parts}                                                                                                        
                     \part $3\sqrt{2}+2\sqrt{2}=\fillin[$5\sqrt{2}$]$                                                                   
                     \part $\sqrt{32}-\sqrt{18}=\fillin[$2\sqrt{2}$]$                                                                   
                     \part $\sqrt{45}+2\sqrt{5}-\sqrt{80}=\fillin[$5\sqrt{5}$]$                                                         
                     \part $\sqrt{28}+2\sqrt{63}-5\sqrt{7}=\fillin[$9\sqrt{7}$]$                                                        
                 \end{parts}                                                                                                          
             \end{multicols}                                                                                                          
         \Question[4] Multiply or Divide:                                                                                             
             \begin{multicols}{2}                                                                                                     
                 \begin{parts}                                                                                                        
                     \part $2\sqrt{3}\times 5\sqrt{6}=\fillin[$30\sqrt{2}$]$                                                            
                     \part $3\sqrt{5}\times 2\sqrt{10}=\fillin[$30\sqrt{2}$]$                                                           
                     \part $14\sqrt{40}\div 7\sqrt{5}=\fillin[$4\sqrt{8}$]$                                                             
                     \part $3\sqrt{2}\div \sqrt{2}=\fillin[$3$]$                                                                        
                 \end{parts}                                                                                                          
             \end{multicols}                                                                                                          
     \end{questions}                                                                                                                  
     \end{doublespace}                                                                                                                
 \end{exercisebox}