# Armstrong number in JavaScript

Armstrong number is a number that is equal to the sum of the nth power of each digit is equal to the given number.

For example:

153, 1634 is amrstrong number. because 13+53+33=153

153=1*1*1+5*5*5+3*3*3 for 3 digits

14+64+34+44=1634 for four digit

### Logic to find Armstrong number of three digits

• Take input from the user and stored it in a variable `n`.
• Copy the value of `n` into the `copy` variable, for later comparing whether number Armstrong or not.
• Iterate the loop until the value of the `copy` variable becomes 0 or less than zero.
• Store the output of the loop into the `sum` variable.
• Check user value i.e `n` is equal to the `sum` or not.
• if it is equal then if statement will get executed and print “It is an Armstrong number”.
• if it's not equal else part gets executed and prints “It is not an Armstrong number”.

## Armstrong number of three digits in JavaScript

In this program, you will take input from users using a window prompt, and you will check whether the number is an Armstrong or not.

``````<!DOCTYPE html>
<html>
<body>
<script>
function Armstrong() {
var r,sum=0,n,copy;
n = parseInt(prompt("enter a number:"));
copy=n;
while (copy>0) {
r=copy%10;
sum=sum+(r*r*r);
copy=parseInt(copy/10);
}
if(n==sum)
{
document.write(n+" is a Armstrong number");
}
else
{
document.write(n+" is not Armstrong a number");
}
}
</script>
<form>
<input type="button" value="ArmstrongNo" onclick="Armstrong();" />
</form>
</body>
</html>
``````

Input has taken through javascript prompt method

## output

```enter a number:153
153 is a Armstrong number
```

## output

```enter a number:123
123 is not Armstrong a number
```

## Check Armstrong number of nth digits in JavaScript

In this program, you will take input from users using a window prompt, and you will check whether the nth digit number is an Armstrong or not.

``````<!DOCTYPE html>
<html>
<body>
<script>
function Armstrong() {
var r,sum=0,n,copy,countdigit=0;
// take input from user
n = parseInt(prompt("enter a number:"));
copy=n;
while(copy>0)
{
// count the number of digit
countdigit++;
copy=parseInt(copy/10);
}
copy=n;
while (copy>0) {
r=copy%10;
// find the power of each individual digit
sum=sum + Math.pow( r, countdigit );
copy=parseInt(copy/10);
}
if(n==sum)   // Check whether the sum is equal to the given number or not
{
document.write(n+" is a Armstrong number");
}
else
{
document.write(n+" is not Armstrong a number");
}
}
</script>
<form>
<input type="button" value="ArmstrongNo" onclick="Armstrong();" />
</form>
</body>
</html>
``````

Input has taken through javascript prompt method

## output

```enter a number:1634
1634 is a Armstrong number
```