**Write a program to find the number is prime or not ?**

Ans : A number which is divisible by 1 and by itself. And not by others is known as prime number

Hint : The idea is to run the loop from 2 to n-1. Check whether n is divisible by any number from (2 to n-1)

var n = 2;

for(var i=2;i<n;i++){

if(n%i==0){

console.log(‘divided by ‘,i)

break;

}

}

console.log(“The i is “,i);

if(n==i){

console.log(“Yes prime”)

}

else{

console.log(“Not prime”);

}

**Write a program to find the prime factorial of a numberExample :315 = 3*3*5*7Solution :**

function primeFactorial(n){

var arr = [];

while(n%2==0){

arr.push(2);

n = n/2;

}

for(var i = 3;i<Math.sqrt(n);i=i+2){

while(n%i==0){

arr.push(i);

n=n/i;

}

}

if(n>2){

arr.push(n);

}

return arr;

}

console.log(“The factorial is “,primeFactorial(27));

**Find the duplicate elements in an array**

function duplicate(arr){

var obj = {};

for(var i=0;i<arr.length;i++){

if(obj[arr[i]]){

obj[arr[i]] = obj[arr[i]] + 1;

}

else{

obj[arr[i]] = 1;

}

}

return obj;

}

var ob = duplicate([1,2,1,2,3,4,5,6]);

console.log(‘The object is ‘,ob);