Summation of Primes

Coding Challenge Level: Beginner

Today's challenge requires you to write code to solve for the summation of prime numbers.

Eg. The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17.

Find the sum of all the primes below n.

Introduction:

As a data scientist or software engineer, you may often encounter coding challenges that require finding the sum of prime numbers. In this article, we will explore an efficient approach to solve this challenge using Python.

Problem Statement:

Given a positive integer 'n', our task is to find the sum of all prime numbers below 'n'. For example, if 'n' is 10, the sum of primes below 10 would be 2 + 3 + 5 + 7 = 17.

Approach:

To solve this problem, we will use a combination of the Sieve of Eratosthenes algorithm and basic arithmetic operations in Python. The Sieve of Eratosthenes is an ancient algorithm used to find all prime numbers up to a given limit.

Code Implementation:

Let's break down the code into logical steps:

1. Create a function called 'sum_of_primes' that takes an input 'n'.
2. Initialize a boolean list, 'is_prime', of size 'n' with all elements set to 'True'. We will use this list to keep track of prime numbers.
3. Initialize a variable, 'sum_primes', to store the sum of prime numbers. Set it to 0.
4. Iterate over numbers from 2 to 'n' using a for loop.
5. Within the loop, check if the current number is marked as prime in the 'is_prime' list. If it is, add it to 'sum_primes' and mark all multiples of that number as non-prime by setting their corresponding 'is_prime' values to 'False'.
6. After the loop ends, 'sum_primes' will contain the sum of all prime numbers below 'n'.
7. Return 'sum_primes' as the final result.

Here's the Python code that implements the above approach:

def sum_of_primes(n):
? ? is_prime = [True] * n
? ? sum_primes = 0


? ? for num in range(2, n):
? ? ? ? if is_prime[num]:
? ? ? ? ? ? sum_primes += num
? ? ? ? ? ? for multiple in range(num * num, n, num):
? ? ? ? ? ? ? ? is_prime[multiple] = False


? ? return sum_primes        

Conclusion:

In this article, we explored how to find the sum of prime numbers below a given value using Python. By leveraging the Sieve of Eratosthenes algorithm, we can efficiently identify prime numbers and calculate their sum. The provided Python code demonstrates an implementation that solves this coding challenge effectively.

Remember, understanding prime numbers and employing algorithms like the Sieve of Eratosthenes can greatly enhance your problem-solving skills.

Thank you for reading this far. To subscribe for more, click?here. Please share in the comment, how you would solve this challenge in your own way. You can include any programming language you are familiar with. Someone might benefit from you.