The magnitude of a complex number, typically expressed as |Formula |z| = √(a² + b²)|, is the distance of the complex number from the origin in the complex plane. It can be calculated using the Formula |z| = √(a² + b²)|Formula |z| = √(a² + b²)| = √(a² + b²), where Formula |z| = √(a² + b²) = a + bi.