Python Program - Check Armstrong Number


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A positive natural number is known as Armstrong number of order $$n$$ if it can be expressed as the sum of each digits of the number raised to the power of $$n$$.


$$A_1A_2A_3...A_n = \sum_{i=0}^n A_i^n = A_1^n+A_2^n+A_3^n+...A_n^n$$


Examples:

$$153 = 1^3+5^3+3^3 = 1+125+27 = 153$$

$$371 = 3^3+7^3+1^3 = 27+343+1 = 371$$

$$1634 = 1^4+6^4+3^4+4^4 = 1+1296+81+256 = 1634$$


Example: Check Armstrong Number

In the below example, the MyNum is checked for Armstrong number using function called ArmStrongNum(). The function requires two parameters, first the number and second the number of digits in it. It calculates power of the digit using the Pow() function. Please see the example below for syntax:

#Calculate power of a digit
def Pow(MyNum, n):
  x = 1
  while n > 0:
    x = x*MyNum
    n = n - 1
  return x

def ArmStrongNum(MyNum, Order):
  y = MyNum
  sum = 0
  while y > 0:
    x = y % 10
    sum = sum + Pow(x, Order)
    y = y // 10
  if MyNum == sum:
    print(MyNum, "is a Armstrong Number.")
  else:
    print(MyNum, "is not a Armstrong Number.")

ArmStrongNum(371, 3)
ArmStrongNum(1634, 4)
ArmStrongNum(1000, 4)

Output

371 is a Armstrong Number.
1634 is a Armstrong Number.
1000 is not a Armstrong Number.

Example: Armstrong Number of order $$n$$

Here, the ArmStrongNum function requires only one parameter, the number itself. The number of digits in the passed number is estimated inside the function. Please see the example below for syntax:

#Calculate power of a digit
def Pow(MyNum, n):
  x = 1
  while n > 0:
    x = x*MyNum
    n = n - 1
  return x

def ArmStrongNum(MyNum):
  y = MyNum
  sum = 0
  Order = 0
  #Find number of digit in the Number
  while y > 0:
    Order = Order + 1
    y = y // 10

  y = MyNum
  while y > 0:
    x = y % 10
    sum = sum + Pow(x, Order)
    y = y // 10
  if MyNum == sum:
    print(MyNum, "is a Armstrong Number.")
  else:
    print(MyNum, "is not a Armstrong Number.")

ArmStrongNum(153)
ArmStrongNum(9474)
ArmStrongNum(5000)

Output

153 is a Armstrong Number.
9474 is a Armstrong Number.
5000 is not a Armstrong Number.




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