What is the alphanumeric representation of the imaginary number?

The story behind the answer

The imaginary unit is denoted by i, defined so that i² = −1. It’s the building block of complex numbers written as a + bi, where a is real and b scales the imaginary unit. By contrast, e is Euler’s constant (~2.718), x is a generic variable, and n typically denotes an integer or count.

Fun context: engineers often write j instead of i to avoid confusion with electric current (also i). A famous memory hook is Euler’s