Python: Find and print the first 10 happy numbers

Last update on April 17 2025 13:05:38 (UTC/GMT +8 hours)

First 10 Happy Numbers

From Wikipedia,
A happy number is defined by the following process:
Starting with any positive integer, replace the number by the sum of the squares of its digits, and repeat the process until the number equals 1 (where it will stay), or it loops endlessly in a cycle which does not include 1. Those numbers for which this process ends in 1 are happy numbers, while those that do not end in 1 are unhappy numbers.
Write a Python program to find and print the first 10 happy numbers.

Sample Solution:

Python Code:

# Function to check if a number is a Happy Number
def happy_numbers(n):
    past = set()  # Set to store previously encountered numbers during the process
    while n != 1:  # Continue the process until the number becomes 1 (a Happy Number) or a cycle is detected
        n = sum(int(i) ** 2 for i in str(n))  # Calculate the sum of squares of each digit in the number
        if n in past:  # If the current number has been encountered before, it forms a cycle
            return False  # The number is not a Happy Number
        past.add(n)  # Add the current number to the set of past numbers
    return True  # If the process reaches 1, the number is a Happy Number

# Print the first 10 Happy Numbers less than 500
print([x for x in range(500) if happy_numbers(x)][:10])

Sample Output:

[1, 7, 10, 13, 19, 23, 28, 31, 32, 44]

Explanation:

Here is a breakdown of the above Python code:

Define a function named "happy_numbers()" that takes a number 'n' as input.
Initialize a set called 'past' to keep track of previously encountered numbers during the process.
Use a while loop to continue the process until the number becomes 1 (a Happy Number) or a cycle is detected.
Inside the loop, calculate the sum of the squares of each digit in the current number.
Check if the current number has been encountered before. If yes, it forms a cycle, and the number is not a Happy Number.
Add the current number to the set of past numbers.
Return 'True' if the process reaches 1, indicating that the number is a Happy Number.
Use a list comprehension to generate the first 10 Happy Numbers less than 500 and print the result.

Visual Presentation:

Python: Find and print the first 10 happy numbers

Flowchart:

For more Practice: Solve these Related Problems:

Write a Python program to generate the first 10 happy numbers by iterating over positive integers.
Write a Python program to collect and display the first 10 numbers that satisfy the happy number condition using a helper function.
Write a Python program to compute happy numbers until 10 such numbers are found, using optimized cycle detection.
Write a Python program to iterate over natural numbers and print the first 10 happy numbers as they are discovered.

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Previous: Write a Write a Python program to check whether a number is "happy" or not.
Next: Write a Python program to count the number of prime numbers less than a given non-negative number.

Python Code Editor:

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