# Day 1: Let and Const Solution

Hello Friends in this article i am gone to share Hackerrank 10 days of javascript solutions with you. | Day 1: Let and Const Solution.

Also visit this link:ย  Day 1: Functions Solution

## Day 1: Let and Const Solution

### Objective

In this challenge, we practice declaring variables using theย letย andย constย keywords. Check out the attached tutorial for more details.

1. Declare aย constant variable,ย PI, and assign it the valueย Math.PI. You will not pass this challenge unless the variable is declared as a constant and namedย PIย (uppercase).
2. Read a number,ย r, denoting the radius of a circle from stdin.
3. Useย PIย andย rย to calculate theย areaย andย perimeterย of a circle having radiusย .
4. Printย areaย as the first line of output and printย perimeterย as the second line of output.

### Input Format

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

### Constraints

• 0 <ย rย <= 100
• rย ย is a floating-point number scaled toย at mostย 3ย decimal places.

### Output Format

Print the following two lines:

1. On the first line, print theย areaย of the circle having radiusย r.
2. On the second line, print theย perimeterย of the circle having radiusย r.

`2.6`

### Sample Output 0

```21.237166338267002
16.336281798666924```

### Explanation 0

Given the radiusย rย = 2.6, we calculate the following:

• areaย = ฯ *ย r^2 = 21.237166338267002
• perimeterย = 2 * ฯ *ย rย = 16.336281798666924

We then printย areaย as our first line of output andย perimeterย as our second line of output.

## Solution โ Day 1: Let and Const

```'useย strict';

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

letย inputStringย =ย '';
letย currentLineย =ย 0;

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

process.stdin.on('end',ย _ย =>ย {
ย ย ย ย inputStringย =ย inputString.trim().split('\n').map(stringย =>ย {
ย ย ย ย ย ย ย ย returnย string.trim();
ย ย ย ย });
ย ย ย ย
ย ย ย ย main();ย ย ย ย
});

ย ย ย ย returnย inputString[currentLine++];
}

functionย main()ย {
ย ย ย ย //ย Writeย yourย codeย here.ย Readย inputย usingย 'readLine()'ย andย printย outputย usingย 'console.log()'.
ย ย ย ย varย rย =ย readLine();
ย ย ย ย //ย Printย theย areaย ofย theย circle:
ย ย ย ย console.log(Math.PIย *ย rย *ย r);
ย ย ย ย //ย Printย theย perimeterย ofย theย circle:
ย ย ย ย console.log(2ย *ย Math.PIย *ย r);

ย ย ย ย tryย {ย ย ย ย
ย ย ย ย ย ย ย ย //ย Attemptย toย redefineย theย valueย ofย constantย variableย PI
ย ย ย ย ย ย ย ย PIย =ย 0;
ย ย ย ย ย ย ย ย //ย Attemptย toย printย theย valueย ofย PI
ย ย ย ย ย ย ย ย console.log(PI);
ย ย ย ย }ย catch(error)ย {
ย ย ย ย ย ย ย ย console.error("Youย correctlyย declaredย 'PI'ย asย aย constant.");
ย ย ย ย }
}```