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

## Example 1: Check Armstrong Number of Three Digits

```
// program to check an Armstrong number of three digits
let sum = 0;
const number = prompt('Enter a three-digit positive integer: ');
// create a temporary variable
let temp = number;
while (temp > 0) {
// finding the one's digit
let remainder = temp % 10;
sum += remainder * remainder * remainder;
// removing last digit from the number
temp = parseInt(temp / 10); // convert float into integer
}
// check the condition
if (sum == number) {
console.log(`${number} is an Armstrong number`);
}
else {
console.log(`${number} is not an Armstrong number.`);
}
```

**Output**

Enter a three-digit positive integer: 153 153 is an Armstrong number.

The above program takes an input from the user. Then,

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

. - A
`while`

loop is used to iterate a three-digit value.- 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,`153 % 10`

gives**3**. - The remainder digit's cube is calculated by multiplying the digit three times. And the cube is added to the
`sum`

variable. - The digit is divided by
**10**to remove the last digit. - The
`while`

loop continues iterating and dividing the number by**10**until the number is**0**.

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

**Note**: In the above program, the cube of a number could be calculated using an exponent operator `**`

. For example, `sum += remainder ** 3;`

## Example 2: Check Armstrong Number of n Digits

```
// program to check an Armstrong number of n digits
// take an input
const number = prompt("Enter a positive integer");
const numberOfDigits = number.length;
let sum = 0;
// create a temporary variable
let temp = 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 == number) {
console.log(`${number} is an Armstrong number`);
}
else {
console.log(`${number} is not an Armstrong number.`);
}
```

**Output**

Enter a positive integer: 92727 92727 is an Armstrong number

In the above program, an Armstrong number of n digits is checked.

When the user enters a number, it is taken as a string. The `length`

property returns the length of a string.

The number entered by the user is stored in a `temp`

variable. And a `while`

loop is used to iterate until its value is less than **0**. Each digit of the number is raised to the power of the length of the number.

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