In file included from main.cpp:8:0:
num.cpp: In member function 'Num& Num::operator=(const Num&)':
num.cpp:10:10: error: no match for 'operator*' (operand type is 'const Num')
   return *other;
          ^~~~~~
In file included from main.cpp:7:0:
num.h:11:9: note: candidate: Num Num::operator*(const Num&)
     Num operator*(const Num& other);
         ^~~~~~~~
num.h:11:9: note:   candidate expects 1 argument, 0 provided
num.h:14:9: note: candidate: Num Num::operator*(int)
     Num operator*(int num);
         ^~~~~~~~
num.h:14:9: note:   candidate expects 1 argument, 0 provided