# JavaScript | Math.expm1() function

Math.expm1() is an inbuilt function in JavaScript which is used to get the value of ep-1, where p is any given number.
The number e is a mathematical constant having an approximate value equal to 2.718.
It was discovered by the Swiss mathematician Jacob Bernoulli.
This number is also called Euler’s number.
Syntax:

`Math.expm1(p)`

Paramter:

• Here p is the parameter and it is any number.
• Return Value:

• It return the value of ep-1, where p is any given number as parameter.

Example:

```Input
Math.expm1(0)
Output
0
```

Explanation
Here the value of parameter p is 0, So after putting the value 0 instead of p in ep-1
then its value becomes 0.

Let’s see JavaScript program:

 `// Here different values is being taken as ` `// as parameter of Math.expm1() function. ` `console.log(Math.expm1(0)); ` `console.log(Math.expm1(1)); ` `console.log(Math.expm1(2)); ` `console.log(Math.expm1(-1)); ` `console.log(Math.expm1(5)); ` `console.log(Math.expm1(2.2)); ` `console.log(Math.expm1(-3.2)); `

/div>

Output:

``` 0
1.718281828459045
6.38905609893065
-0.6321205588285577
147.4131591025766
8.025013499434122
-0.9592377960216338
```

Error Or NaN:

• Here parameter should must be a number otherwise it give error or NaN i.e, not a number.
Code #1:

 `// Here alphabet parameter give error. ` `console.log(Math.expm1(C)); `

Output:

`Error: C is not defined`
• Code #2:
 `// Here parameter as a string give NaN. ` `console.log(Math.expm1(``"geeksforgeeks"``)); `

Output:

`> NaN`
• Application:

• Whenever we need to find the value of ep-1, where p is any given number that time we take the help of Math.expm1() function in JavaScript.
 `// Here different numbers are being taken as parameter ` `// from 0 to 9 for Math.expm1() function. ` `for` `(i = 0; i < 10; i++) { ` `    ``console.log(Math.expm1(i)); ` `    ``+``"
"``; ` `} `

Output:

``` 0
1.718281828459045
6.38905609893065
19.085536923187668
53.598150033144236
147.4131591025766
402.4287934927351
1095.6331584284585
2979.9579870417283
8102.083927575384
```