This official free plugin by Microsoft is simply amazing. This is for Word and OneNote 2007 & 2010. Those who use OneNote already know that if u enter a simple arithmetic equation it calculates automatically. such as you type “2+3=” and press the space bar and OneNote will fill in the result “5” at the end. However, this does not work in Word. It is particularly important in Word since a lot of reports are written in Word and may require calculations. You can use the equation editor and just solve the equations using this plug-in.
This plugin goes beyond this. you can enter any equation with any number of variables and it can either solve for all the variables, plot 2D or 3D graphs. you can enter a table of data and plot simple graphs. Calculates complex arithmetic, integration, differentiation, complex integrals, etc.
Very simple to use, enter the equation in Equation editor and right click the equation and select the calculation to perform. for multiple equations, select multiple equations. It recognises subscripts as variables and superscripts as powers. I have found this plug-in very useful for my university work. Really this is for anyone who works with a lot of math.
Hope you find this plugin very useful.
Source: MS Office Maths Plug-in