Pi. π. 3.14159. A mathematical constant; an infinite number – the ratio of a circle’s circumference to its diameter. Records of its use date back to Babylon and Egypt, as early as 1900 BCE, and both civilizations developed approximations within 1% of pi’s true value, and the number has proved infinitely important to both maths and science – whilst it’s use can be as simple as helping to calculate the diameter of a circle in a maths class, or for laying foundations to a circular building, we have been able to use the number for far greater purposes: in calculating the circumference of the earth, for example.

The most interesting thing about pi, however, is its irrational nature: it can never be expressed as a ratio of two integers – thus, it’s decimal representation never ends, and it can never settle into a permanent repeating pattern. As of late 2011, scientists have extended pi’s decimal representation to THIRTEEN TRILLION digits. That amount alone is incomprehensible to all but the most skilled mathematicians – I can’t begin to comprehend its enormity.