To find the symbol for pi and have an easier time typing it on your iPhone, you'd have to add the Greek keyboard to your mobile device. Here's how: Launch the Settings app. Go to General. Select ...

The Phaistos disk from circa 1700 B.C. The signs were not engraved using a stylus but rather pressed onto the wet clay using molds or seals in a kind of ancient typesetting.

Eventually the plus and minus signs became universal, as did the English symbol for equality, but only after decades of famous mathematicians competing in these popularity contests to set the trends.