A positive integer is called an Armstrong number (of order **n**) if:

abcd... = a^{n}+ b^{n}+ c^{n}+ d^{n}+ ...

In the case of an Armstrong number of 3 digits, the sum of cubes of each digit is equal to the number itself. For example, **153** is an Armstrong number because:

153 = 1*1*1 + 5*5*5 + 3*3*3

Similarly, **1634** is an Armstrong number because:

1634 = 1*1*1*1 + 6*6*6*6* + 3*3*3*3 + 4*4*4*4

Before trying this program, visit JavaScript Program to Check Armstrong Number.

## Example: Armstrong Numbers Between Two Intervals

```
// program to find Armstrong number between intervals
// take an input
let lowNumber = parseInt(prompt('Enter a positive low integer value: '));
let highNumber = parseInt(prompt('Enter a positive high integer value: '));
console.log ('Armstrong Numbers:');
// looping through lowNumber to highNumber
for (let i = lowNumber; i <= highNumber; i++) {
// converting number to string
let numberOfDigits = i.toString().length;
let sum = 0;
// create a temporary variable
let temp = i;
/* loop through a number to find if
a number is an Armstrong number */
while (temp > 0) {
let remainder = temp % 10;
sum += remainder ** numberOfDigits;
// removing last digit from the number
temp = parseInt(temp / 10); // convert float into integer
}
if (sum == i) {
console.log(i);
}
}
```

**Output**

Enter a positive low integer value: 8 Enter a positive high integer value: 500 Armstrong Numbers: 8 9 153 370 371 407

In the above program, the user is prompted to enter two integers. One is the lower interval integer and another is the higher integer value.

The `parseInt()`

converts the numeric string value to an integer value.

The `for`

loop is used to loop through the two numbers provided by the user.

The `toString()`

method is used to convert a number to a string. And `length`

property is used to find the total digits in a number.

`let numberOfDigits = i.toString().length;`

In the first `for`

loop iteration (**i = 8**),

- The lower number entered by the user is stored in a temporary variable
`temp`

. - A
`while`

loop is used to iterate the number.- The
**modulus operator**`%`

is used to obtain each digit number. When a number is divided by**10**, the remainder is the last digit. In the first iteration,`8 % 10`

gives**8**. - The remainder is multiplied by the number of digits in that number(here
**1**) and the sum is calculated. - The digit is divided by
**10**to remove the last digit, i.e.`8 / 10`

gives 0.

- The
- Finally, the sum is compared with the number entered by the user. If the sum and the number are equal, the Armstrong number is displayed.

The loop continues for all the in between numbers that the user provides. In the above example, the loop is executed for **8** to **500**.