Happy Grader Keyboard!

Happy Grader Keyboard provides you with a simple keyboard with many useful math symbols. It will fulfill all of your math needs with numbers, superscripts, pi, math operators and relations, infinity, and beyond. Install the app first, then to setup the keyboard go to Settings > General > Keyboard > Keyboards > Add New Keyboard > Happy KeyCredit for the keyboard functionality and design goes to the open source Tasty Imitation Keyboard by Alexei Baboulevitch (GitHub user archagon).