This can be used to evaluate the expression currently in the window.

It does NOT work on equations ( ie if there is an equals sign in the
expression then this function will always return zero ).

The program will need to know what values to substitute in for any
variables used in the expression. When you have entered these then
press "EVALUATE" and the expression will be calculated.

There is also the option to  graph the function. The graph
works on the same values for variables as the evaluator.