A blank canvas is a perfect representation of a number the value of which we cannot even estimate

An unknown number is a number, the exact or sometimes even an approximate value of which remains a mystery. Famously designated as “x” in many math texts, it can also be denoted as a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, v, w, y or even z.

A great deal of things in the world can be described by an unknown number, including the exact amount of turtles on planet Earth, as well as the number of people who have never heard of a cactus.