**`exp()`** is a `dart:math` package function that returns the natural exponent, $e$, to the power of a specified number.

# 
## Syntax

The syntax of the `exp()` method is as follows:

```dart
double exp(num x)
```

## Parameters

* `num x`: A mandatory numerical value that serves as the power to which the natural exponent, $e$, is raised.

## Return value

`exp()` returns the natural exponent, $e$, raised to the power of `x`. The result is returned as a `double`.

`exp()` returns `NaN` (Not-A-Number) if `x` is also `NaN`.

## Code

In the code below, we will demonstrate the use of the `exp()` method:

// Importing the dart math package
import "dart:math";

// Main function
void main(){

  // Not NaN values or real values
  double no1 = 4.00; // Real Number
  double no2 = 100.00; // Real Number
  double no3 = 3.50; // Real Number

  // NaN Values
  double no4 = 0/0; // NaN
  double no5 = pow(-2, 0.5); // NaN

  // Print values returned by the exp() function
  print(exp(no1));
  print(exp(no2));
  print(exp(no3));
  print(exp(no4));
  print(exp(no5));
}

#    
## Explanation

In the code above, we call the `exp()` method with both numerical and `NaN` arguments.

The function calls to the `exp()` method in lines $17-19$ return the value of the natural exponent, $e$, raised to the power of the provided parameter.

On the other hand, the function calls in lines $20-21$ provide `NaN` as the argument, so the `exp()` method also returns `NaN`.

What is the exp() method in Dart?

Returns the natural exponent e to the power of a given number or NaN if input is NaN.