Consider using MathType! It will have full functionality for 30 days, and thereafter the light mode will keep running, no need to pull your creditcard. It will be still be very usable though, and most claim that Mathtype 'light' is still better than the full MS Equation editor!
The software works with another variety of programs, including Google docs.
http://www.dessci.com/ is the link for download
And while we are at it, get the dust of your iPad (really?) and explore the goodies out there:
http://www.walkingrandomly.com/?p=2692
or
http://appsineducation.blogspot.com/p/maths-ipad-apps.html
