In JavaScript, `NaN`

represents a value which is **not a number**.

Sometimes, we might perform arithmetic operations on values which are not numbers. In such cases, the result is **Not a Number** or **NaN**.

In the example given below, the value stored in the `num`

variable contains alphabets along with numbers.

This means that the value of `num`

is not a proper number. Therefore, if we perform any arithmetic operations, it returns `NaN`

.