# Armstrong Number

What is an Armstrong number ?

A number equal to sum of the power of 3 of its digits. ( for 3 digit number )
A number equal to sum of the power of 4 of its digits. ( for 4 digit number )

A number equal to sum of the power of n of its digits. ( for n digit number )

## Example 1:

153=13 + 53 + 33
153=1 + 125 + 27
So 153 is an Armstrong number

## 3 digit Armstrong number

Ask user to enter a 3 digit number and then display if it is an Armstrong number or not.
``````n=input(" Enter one three digit number ")
sum=0
for i in range(0,len(n)):
sum=sum+pow(int(n[i]),3)

print("Sum of cube of digits  : ",sum)
if(sum==int(n)):
print("This is an Armstrong number : ", n)
else:
print("This is an NOT an Armstrong number : ", n)``````
By using pow() function we can get the power of two input numbers.
By using len() we can check the number of digits used in the input number ( string data type).
Note that all input numbers are string data type by default. We can convert string to integer by suing int() function.

## Armstrong number of any number of digits

``````n=input(" Enter any number more than 9  ")
sum=0
k=len(n)
for i in range(0,k):
sum=sum+pow(int(n[i]),k)

print("Sum of cube of digits  : ",sum)
if(sum==int(n)):
print("This is an Armstrong number : ", n)
else:
print("This is NOT an Armstrong number : ", n)``````

## All Armstrong numbers within a range

List all the Armstrong numbers less than 10000 ( increase the upper limit below )
``````for n in range(10,10000): # increase this range to get more numbers
sum=0
my_str=str(n)
k=len(my_str)
for i in range(0,k):
sum=sum+pow(int(my_str[i]),k)

#print("Sum of cube of digits  : ",sum)
if(sum==n):
print("This is an Armstrong number : ", n)``````
Output
``````This is an Armstrong number :  153
This is an Armstrong number :  370
This is an Armstrong number :  371
This is an Armstrong number :  407
This is an Armstrong number :  1634
This is an Armstrong number :  8208
This is an Armstrong number :  9474``````

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