# A to Z of Excel Functions: The IMAGINARY Function

6 July 2020

*Welcome back to our regular A to Z of Excel Functions blog. Today we look at the IMAGINARY function. *

**The IMAGINARY function**

An imaginary number is a complex number that can be written as a real number multiplied by the imaginary unit **i **(sometimes denoted **j**) which is defined by its property **i ^{2}** = −1. In general, the square of an imaginary number

**bi**is

**−b**. For example, 9

^{2}**i**is an imaginary number, and its square is −81. Zero is considered to be both real and imaginary.

An **imaginary** number **bi** can be added to a **rea**l number **a** to form a **complex number** of the form **a + bi**, where the real numbers **a** and **b** are called, respectively, the **real** part and the **imaginary** part of the **complex number**.

The **IMAGINARY **function really does exist, and it returns the imaginary coefficient of a complex number in the form **a + bi**.

The **IMAGINARY **function employs the following syntax to operate:

**IMAGINARY(inumber)**

The **IMAGINARY** function has the following argument:

**inumber:**this is required and represents the complex number for which you want the imaginary coefficient.

It should be further noted that:

- you should use
**COMPLEX**to convert real and imaginary coefficients into a complex number **IMAGINARY**recognises either the**i**or**j**notation- if the complex number ends in +
**i**or -**i**(or**j**),*i.e.*there is no coefficient between the operator and the imaginary unit, there must be no space, otherwise**IMAGINARY**will return an*#NUM!*error.

Please see my example below:

*We’ll continue our A to Z of Excel Functions soon. Keep checking back – there’s a new blog post every business day.*

*A full page of the function articles can be found here. *