Day 1: Let and Const | 10 Days of JavaScript – Hacker Rank Solution

Day 1: Let and Const | 10 Days of JavaScript – Hacker Rank Solution: Hey Guy’s In this post we are solving Day 1: Let and Const – HackerRank Solution which is a part of 10 Days of JavaScript Series.

Day 1: Let and Const | 10 Days of JavaScript – Hacker Rank Solution

Day 1: Let and Const JavaScript


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


  1. 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. 2. Read a number, r, denoting the radius of a circle from stdin.
  3. 3. Use PI and r to calculate the area and perimeter of a circle having radius r.
  4. 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.


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

Output Format

Print the following two lines:

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

Sample Input 0


Sample Output 0



Explanation 0

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

  • area = π x r2 = 21.237166338267002
  • perimeter = 2 x π x r = 16.336281798666924

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

Day 1: Let and Const | 10 Days of JavaScript – Hacker Rank Solution

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

Disclaimer: The above Problem (Day 1: Let and Const) is generated by Hackerrank but the Solution is Provided by Chase2Learn. This tutorial is only for Educational and Learning purposes. Authority if any of the queries regarding this post or website fill the following contact form thank you.

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