A design created in celebration of ? -day, 2019. (More context about the day here and more about the number itself here). As always, the OofSI team celebrates Pi(e) day by offering a selection of ? s – exactly at 1:59 PM. Totally irrational I know!
Apart from being irrational, ? is also a transcendental number, which means it is not the root of any polynomial having rational coefficients. This implies, mathematicians argue, that it is impossible to solve the ancient challenge of squaring the circle. I beg to differ, as I so (tongue-in-cheek-ingly) proved in this blog post from last year.