Answer 1

If you want to output a result from expression evaluation, you could wrap it up in parentheses.

System.out.println( " " + ( 6 + 7 ) );

Answer 2

Verstappen JVM understand may u want to add numbers as string . If you put brackets to (6+7) then it treat as may be programmer want to add numbers.

Answer 3

Because the compiler after the quotes interprets the + symbol as a string concatenation character and automatically converts to a string everything that comes after the concatenation character, the result is "" + "6" + "7"