The letter "i" is used to signify that a number is an imaginary number.
Step-by-step explanation:
An imaginary number is one that gives a negative result when squared. This differs from when you square real numbers where you always get a positive result. For example:
i = √-1
Imaginary numbers can be especially useful when trying to find the square root of a real negative number such as -16. Normally we cannot find the square root of -16 but through the use of imaginary numbers we can:
