Program to check if the given number is Happy Number in Python. This program contains functions, if else conditional statements and while loop. This program is for beginners, class 11,12 and B Tech students. Download free source code from this site.

### What is Happy numbers ?

In number theory, a **Happy number** is a number which eventually reaches 1 when replaced by the sum of the square of each digit. For instance, 13 is a happy number because , and . On the other hand, 4 is not a happy number because the sequence starting with and eventually reaches , the number that started the sequence, and so the process continues in an infinite cycle without ever reaching 1. A number which is not happy is called **sad** or **unhappy**.

### Source code :

```
def isHappyNumber(num):
rem = sum = 0
while(num > 0):
rem = num%10
sum = sum + (rem*rem)
num = num//10;
return sum;
num = int(input("Enter the n.o to checked happy or sad"))
result = num
while(result != 1 and result != 4):
result = isHappyNumber(result)
if(result == 1):
print(str(num) + " is a happy number")
elif(result == 4):
print(str(num) + " is not a happy number")
```

### Step wise source code Explanation :

**Step 1: isHappyNumber() will determine whether a number is happy or not**

def isHappyNumber(num):

rem = sum = 0**Step 2: Calculates the sum of squares of digits**

while(num > 0):

rem = num%10

sum = sum + (rem*rem)

num = num//10;

return sum;

num = int(input(“Enter the n.o to checked happy or sad”))

result = num

while(result != 1 and result != 4):

result = isHappyNumber(result)**Step 3: Happy number always ends with 1**

if(result == 1):

print(str(num) + ” is a happy number”)**Step 4:Unhappy number ends in a cycle of repeating numbers which contain 4**

elif(result == 4):

print(str(num) + ” is not a happy number”)

### Output :

Python 3.7.4 (tags/v3.7.4:e09359112e, Jul 8 2019, 19:29:22) [MSC v.1916 32 bit (Intel)] on win32 Type "help", "copyright", "credits" or "license()" for more information. >>> RESTART: C:/csstudy/download source code files/Program to check if the given number is Happy Number in Python.py Enter the n.o to checked happy or sad37 37 is not a happy number >>> RESTART: C:/csstudy/download source code files/Program to check if the given number is Happy Number in Python.py Enter the n.o to checked happy or sad32 32 is a happy number >>>

### Output Explanation:

Step 1 :Input is captured

Enter the n.o to checked happy or sad32

Step 2 :After calculation in the backend it is printed on the screen

32 is a happy number

### Conclusion :

This program runs fine.

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