Microsoft Math Add-in for Word is a simpler and free version of Microsoft Math (a full-featured and advanced graphic calculator for PC). This add-on is very simple to use, as it uses Word's well-known Interface. Since keyboards are not designed for writing equations, Microsoft developed a whole Menu of options where you can find almost every possible alternative, from matrices to integrals or fractions.
After entering your mathematical expression, you simply invoke the add-on and let it do its job. At present, Math Add-On for Word allows simplification, calculating an integral, derivation and graphing the expression in 2D or 3D. Notice that, unlike most graphic calculators, this add-on does not limit itself to drawing a derivative or an integral, but in fact provides the whole expression of an integral, a solution one is supposed to write in, for instance, school quizzes (Microsoft Math is primarily aimed at schoolchildren). After drawing a graph or simplifying an expression, you have the possibility to edit that result, like any other Word element that you type yourself.