Multiplying numbers given by the user can be done as shown below:

   

Multiplications with variables can be done as shown on the image below:

   

Multiplications with values can be done as shown on the image below:

   

Now we will ask the user for two numbers and subtract them from each other as shown on the image below:

   

We will continue with variables.
Variables can be subtracted as shown on the image below:

   

We will start with values again.
Subtractions with values can be done as shown on the image below:

   

Of course we can ask the user to enter two numbers and add them, too.
Have a look at the image shown below:

   

Additions can also be done by adding two variables as shown on the image below:

   

Now we will let the computer do what it can do best -> calculations.
Additions can be done by just adding two values as shown on the image below:

   

The third option to print "Hello, World!" on the screen is asking the user for input and printing that on the screen as shown on the image below: