Happy Number In Python

Python Program To Check Happy number or Not

In Number Theory, A Happy Number is a Number Which
Eventually reaches 1 when replaced by the sum of the square of each digit.

Example :
Given Number : 13
13 is a Happy Number
Because
13 = ( 1*1 )+( 3*3 ) = 1 + 9 = 10
10 = ( 1*1 )+( 0*0 ) = 1 + 0 = 1

Given Number : 28
28 is a Happy Number
Because
28 = ( 2*2 ) +( 8*8 ) = 4 + 64 = 68
68 = ( 6*6 ) +( 8*8 ) = 36+ 64 = 100
100= ( 1*1)+( 0*0 )+ ( 0*0) = 1 + 0 + 0 = 1

Algorithm to check if a number is a Happy Number or Not in Python
you can use the following algorithm:

1. Read the input number.
2. Initialize a variable sum to 0.
3. Create a copy of the input number.
4. While num is not equal to 0, perform the following steps:
• Get the last digit of the num by using the modulo operator (%).
• Square the last digit and add it to sum.
• Divide the num by 10 to remove the last digit.
• if num = 0 and sum>=10
• Reset num to sum and sum to 0.
5. Check if the sum of the number is equal to 1.
• If it is 1, the number is a Happy Number.
• If it is Not 1, the number is Not a Happy Number.

Please note that this implementation assumes that the input number is a positive integer. You may need to add additional checks for negative numbers or other cases depending on your requirements.

Here is an example implementation in Python:

Source Code

# Python Program to Check Happy Number or Not
num = int(input("Enter a Number To Check : "))
Sum=0
while num!=0:
    Rd = num%10
    Sum=Sum+Rd**2
    num=num//10
    if num==0 and Sum>9:
        num=Sum
        Sum=0
if Sum==1:
    print("It is a Happy Number . ")
else:
    print("It is Not a Happy Number . ")

Output

Sample Input :
Enter a Number To Check : 28
Sample Output:
It is a Happy Number

Sample Input :
Enter a Number To Check : 13
Sample Output:
It is Not a Happy Number

Sample Input :
Enter a Number To Check : 12
Sample Output:
It is Not a Happy Number