> For the complete documentation index, see [llms.txt](https://dailyjournal.gitbook.io/solutions/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://dailyjournal.gitbook.io/solutions/hackerrank-solutions/tutorials/10-days-of-javascript/day-1.md).

# Day 1

## Arithmetic Operators

{% embed url="<https://www.hackerrank.com/challenges/js10-arithmetic-operators?isFullScreen=true>" %}

```javascript
/**
*   Calculate the area of a rectangle.
*
*   length: The length of the rectangle.
*   width: The width of the rectangle.
*   
*	Return a number denoting the rectangle's area.
**/
function getArea(length, width) {
    let area;
    // Write your code here
    area = length * width;
    return area;
}

/**
*   Calculate the perimeter of a rectangle.
*	
*   length: The length of the rectangle.
*   width: The width of the rectangle.
*   
*	Return a number denoting the perimeter of a rectangle.
**/
function getPerimeter(length, width) {
    let perimeter;
    // Write your code here
    perimeter = 2 * (length + width);
    return perimeter;
}
```

## Functions

{% embed url="<https://www.hackerrank.com/challenges/js10-function/problem?isFullScreen=true>" %}

```javascript
/*
 * Create the function factorial here
 */
function factorial(n){
    return n ? n * factorial(n - 1) : 1;
}
```

## Let and Const

{% embed url="<https://www.hackerrank.com/challenges/js10-let-and-const/problem?isFullScreen=true>" %}

{% code overflow="wrap" %}

```javascript
function main() {
    // Write your code here. Read input using 'readLine()' and print output using 'console.log()'.
    const PI = Math.PI;
    let r = readLine(); 
    // Print the area of the circle:
    console.log(PI * r * r);
    // Print the perimeter of the circle:
    console.log(2 * PI * r);
    try {    
        // Attempt to redefine the value of constant variable PI
        PI = 0;
        // Attempt to print the value of PI
        console.log(PI);
    } catch(error) {
        console.error("You correctly declared 'PI' as a constant.");
    }
}
```

{% endcode %}


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://dailyjournal.gitbook.io/solutions/hackerrank-solutions/tutorials/10-days-of-javascript/day-1.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.