# R Program to find
Armstrong Number

In
this article you will learn how to check if a number is Armstrong or
not in R Programming with the help of if else structure and while loop.

## What is an Armstrong Number?

A number is
said to be Armstrong if the sum of cubes of its digits is equal to the
number itself.

See
the example of 153, we want to check if it is an Armstrong number first
we will find the cubes of its digits and then add them together to see
the sum. If the sum is 153 i.e. equal to the number itself then it is
an armstrong number else its not.

Now 153
consists of three digits 1, 5 and 3. First we will take cube of these
three digits and then add the values.

153

Digits:

1, 5, 3

Cubes of
digits and sum:

= (1)^{3}+
(5)^{3} + (3)^{3}

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

= 1 + 125 + 27

= 153

The sum of cubes of all
individual digits is equal to the number itself, hence 153 is an
Armstrong number.

## Armstrong Number Check
Calculation:

Similarly to find if 23 is an
armstrong number or not. We will take cube of 2 and 3 and then add the
values.

Cubes of
digits and sum:

= (2)^{3}+ (3)^{3}

= 2*2*2
+ 3*3*3

= 8 + 27

= 35

35 is the sum of cubes and as
it is not equal to the number itself hence 23 is not an armstrong
number.

After these two examples, now
it is very clear what is an armstrong number and how to check it by
calculation.

## Example
: Find Armstrong Number

Now here is R
code to check if a number is armstrong.

isArmstrong <-
function(x){

sum <- 0

y <- x

while(y > 0){

digit <- y %% 10

sum <- sum + (digit^3)

y <- floor(y/10)

}

if(x == sum){

print(paste(x,' *** is an Armstrong
Number ***'))

} else {

print(paste(x,'is not an Armstrong
Number'))

}

} # Function

isArmstrong(153)

isArmstrong(23)

### Output:

>
isArmstrong(153)

[1]
"153 *** is an Armstrong Number ***"

>
isArmstrong(23)

[1]
"23 is not an Armstrong Number"

#### Explanation:

First we
define a function isArmstrong and initialize sum to 0.

We get each
digit of number with the help of mod or modulus operator %%. Take cube of each digit and
add it in sum.

Remainder is the last digit
when it is divided by 10.

If else is
used to see if sum of all cubes is equal to the number itself.

### RStudio
Armstrong Number Code and its Output:

Here is
RStudio working code to find armstrong number.

Learn R is
the place to learn R for all purposes from simple analytics to data
science and machine learning.

^{}