Looping problems in JS

Looping programs

1) 1 1 1 1 1

let i=1;
let str="";
while(i<=5){
    str=str+" "+1;
    i++;
}
console.log(str)

output:

1 1 1 1 1

---

2) 1 2 3 4 5

let i=1;
let str="";
while(i<=5){
    str=str+" "+i;
    i++;
}
console.log(str)

output:

1 2 3 4 5

---

3) 1 3 5 7 9

let i=1;
let num=1;
let str="";
while(num<=5){
    str=str+" "+i;
    i=i+2;
    num++;
}
console.log(str);

output:

1 3 5 7 9

---

4) 3 6 9 12 15

let i=3;
let num=1;
let str="";
while(num<=5){
    str=str+" "+i;
    i=i+3;
    num++;
}
console.log(str);

output:

3 6 9 12 15

---

5) Multiples of 3 and 5

let i=1;
while(i<=100){
    if(i%3==0 && i%5==0){
        console.log(i);
    }
    i++;
}

output:

15
30
45
60
75
90

---

6) Multiples of 3 or 5

let i=1;
while(i<=20){
    if(i%3==0 || i%5==0){
        console.log(i);
    }
    i++;
}

output:

3
5
6
9
10
12
15
18
20

---

7) Divisors of given number

let num=51;
let i=1;
while(i<=num){
    if(num%i==0){
       console.log(i); 
    }
    i++;
}

output:

1
3
17
51

---

8) Count of Divisors of given number

let num=8;
let i=1;
let count=0;
while(i<=num){
    if(num%i==0){
       count++;
    }
    i++;
}
console.log(count);

output:

4

---

9) Prime Number

let num=31;
let i=2;
let isprime=true;
while(i<=num/2){
   if(num%i==0){
       isprime=false;
   }
   i++; 
}
console.log(isprime?"Prime number":"Not a prime");

output:

Prime number

---

10) Reverse Printing a number

let num=2004;

while(num>0){               
    let digit=num%10;   
    console.log(digit);
    num=Math.floor(num/10);  
}

output:

4
0
0
2

---

11) Count of Digits

let num=5305;
let count=0;
while(num>0){
    count++;       
    num=Math.floor(num/10);    
}
console.log(count);

output:

4

---

12) Sum of Digits

let num=127;
let sum=0;
while(num>0){
    let digit=num%10;
    sum=sum+digit;
    num=Math.floor(num/10);
}
console.log(sum);

output:

10

---

13) Reverse the number

let num=4002;
let reverse=0;                      
while(num>0){               
    let digit=num%10;   
    reverse=reverse*10+digit;      
    num=Math.floor(num/10);  
}
console.log(reverse);

output:

2004

---

14) Palindrome

let num=121;
let n=num;
let reverse=0;
while(n>0){
    let digit=n%10;
    reverse=reverse*10+digit;      
    n=Math.floor(n/10);
}

if(num == reverse){
    console.log(reverse+" Is a Palindrome");
}
else{
    console.log(reverse+"Is not a palindrome");
}

output:

121 Is a palindrome

---

15) Armstrong Number

let num=153;        
let strnum=String(num);
let digit=strnum.length;
let sum=0;
while(num>0){
   let last=num%10; 
   sum=sum+Math.pow(last,digit); 
   num=Math.floor(num/10);
}
if(strnum==sum){
    console.log(strnum+" Armstrong number");
}
else{
    console.log(strnum+" Not Armstrong number");
}

output:

153 Armstrong number