my coding doesn't work plz help

[wavic]

It is possible to define a function into another function but is pointless in your case. Rid of all these math functions which are doing one thing, to return a calculation result of two values. There is no indentation of elif to if

  if(operation == '+'):
      return num1 + num2
  elif(operation == '-'):
      return num1 - num2
  elif(operation == '*'):
      return num1 * num2
  else:
      return num1 / num2
......

print(calculator())

Also, you call calculator() inside its own code. Use while loop instead.
For now, that's all.

All in all, I'd have a different approach to almost everything.