This Pen

This Pen is the one-hundred-twenty-second episode of Numberstairs.

Plot
A magic pen appears and writes mathematical signs.

Facts
The signs that the pen writes are +, -, =, x, /, ^, the square root sign, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, the Pi symbol, the Tau symbol, e, the golden ratio symbol, i, j, parentheses, and everything else you can imagine.