# Day 1: Let and Const | 10 Days of JavaScript | HackerRank Solution

Hello coders, today we are going to solve Day 1: Let and Const HackerRank Solution which is a part of 10 Days of JavaScript Series.

## Objective

In this challenge, we practice declaring variables using the let and const keywords. Check out the attached tutorial for more details.

1. Declare a constant variablePI, and assign it the value Math.PI. You will not pass this challenge unless the variable is declared as a constant and named `PI` (uppercase).
2. Read a number, r, denoting the radius of a circle from stdin.
3. Use PI and r to calculate the area and perimeter of a circle having radius .
4. Print area as the first line of output and print perimeter as the second line of output.

## Input Format

A single integer, r, denoting the radius of a circle.

## Constraints

• 0 < r <= 100
• r  is a floating-point number scaled to at most 3 decimal places.

## Output Format

Print the following two lines:

1. On the first line, print the area of the circle having radius r.
2. On the second line, print the perimeter of the circle having radius r.

Sample Input 0

``2.6``

Sample Output 0

``````21.237166338267002
16.336281798666924``````

Explanation 0

Given the radius r = 2.6, we calculate the following:

• area = Ï€ * r^2 = 21.237166338267002
• perimeter = 2 * Ï€ * r = 16.336281798666924

We then print area as our first line of output and perimeter as our second line of output.

## Solution – Day 1: Let and Const

```'use strict';

process.stdin.resume();
process.stdin.setEncoding('utf-8');

let inputString = '';
let currentLine = 0;

process.stdin.on('data', inputStdin => {
inputString += inputStdin;
});

process.stdin.on('end', _ => {
inputString = inputString.trim().split('\n').map(string => {
return string.trim();
});

main();
});

return inputString[currentLine++];
}

function main() {
// Print the area of the circle:
console.log(Math.PI * r * r);
// Print the perimeter of the circle:
console.log(2 * Math.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.");
}
}```

Disclaimer: The above Problem (Let and Const) is generated by Hacker Rank but the Solution is provided by CodingBroz. This tutorial is only for Educational and Learning Purpose.