This is pretty user friendly so you can start by just entering some math problems. This program will even help
prevent creating an invalid expression. The following should clear things up if you have any problems.
Math operators and parentheses do not show up in the input field. They are automatically added to the current
calculation along with any value in the input field, as long as it fits a valid mathematic expression. Starting
with a minus sign when the last thing in the expression is not a number will start a negative number within the
input field.
If the input field is empty, backspace will delete the last thing in the expression.
Once the whole expression is entered, click 'calculate' or hit the 'Enter' key (or 'Go' on portable devices) to
calculate the expression. The program will notify you if the expression is not a valid math expression.
Once a result is found, entering a number first will start a new expression. Entering a math operator first will
cause the new expression to start with the previous result. The later is in keeping with the original exercise
given in this
course. This applies even if a left-parentheses is actually entered first.