Answer 1

If you are in a Python command line interpreter ( kind of console/terminal, lines beginning with some prompt like '>>>' ), typing '6+3' is enough ( if you validate by [enter] key ) to print the result of the expression, as the value of a variable by just typing its identifier name...

But if you are writing script in text file ( what's the virtual case of code playground as well ), this isn't enough ( in addition to run/execute the script ) to output anything... To do it, you must use the print() function:

print(6+3)