You would find it easier if you used the % tags as in "formatting output" in this
Java™ Tutorials section.
I would suggest you can simplify your code:
You only need one Scanner object.Produce an operator String. You can have operator = "+"; or similar in your switch-case.Then you only need one line which prints the result, after the end of the switch. You will get peculiar output if anybody enters 5, however!Without changing anything like that, your problem is that you have results to be printed out which start with a number, and you want a String. To make them into Strings, try starting with the empty String "" and put that with a + at the beginning of each of your lines to print the result.
You are also short of a + sign in each of those print statements; it shows the hazards of copy-and-paste; you have copied the error into all the statements.
If you have only been doing Java for 3 days, it is hardly surprising you haven't worked out how to write a loop yet.