SciKey is a Scientific Keyboard that brings you the essential scientific characters for your iPad, iPhone, and iPod touch.
Fully customizable, with more than 3,000 characters to choose from, to build your perfect keyboard (requires in-app purchase).
It includes Greek and Latin letters, mathematical symbols, emoji and much more missing from the standard iOS keyboard. It also works for text snippets.
You can use it from all your applications: on the web, composing emails, taking notes, writing your next publication... it simply works everywhere.