# Python: Compute the sum of first n given prime numbers

## Python Basic - 1: Exercise-52 with Solution

Write a Python program to compute the sum of the first n prime numbers.

**Input:**

n ( n ≤ 10000). Input 0 to exit the program.

Input a number (n≤10000) to compute the sum:(0 to exit)

25

Sum of first 25 prime numbers:

1060

**Visual Presentation:**

**Sample Solution**:

**Python Code:**

```
# Set the maximum limit for prime number computation
MAX = 105000
# Print statement to prompt the user to input a number (n≤10000) to compute the sum (0 to exit)
print("Input a number (n≤10000) to compute the sum:(0 to exit)")
# Boolean list to track prime numbers using the Sieve of Eratosthenes algorithm
is_prime = [True for _ in range(MAX)]
is_prime[0] = is_prime[1] = False
# Iterate through the range to mark non-prime numbers
for i in range(2, int(MAX ** (1 / 2)) + 1):
if is_prime[i]:
for j in range(i ** 2, MAX, i):
is_prime[j] = False
# Create a list of prime numbers within the given range
primes = [i for i in range(MAX) if is_prime[i]]
# Infinite loop to continuously accept user input until 0 is entered
while True:
# Prompt the user to input a number
n = int(input())
# Check if the entered number is 0, and exit the loop if true
if not n:
break
# Print statement to display the sum of the first n prime numbers
print("Sum of first", n, "prime numbers:")
# Calculate and print the sum of the first n prime numbers using list slicing
print(sum(primes[:n]))
```

Sample Output:

Input a number (n≤10000) to compute the sum:(0 to exit) 25 Sum of first 25 prime numbers: 1060

**Explanation:**

Here is a breakdown of the above Python code:

- First the code sets the maximum limit for prime number computation (MAX).
- It initializes a boolean list (is_prime) to track prime numbers using the Sieve of Eratosthenes algorithm.
- The code creates a list of prime numbers (primes) within the specified range.
- It enters an infinite loop to continuously accept user input until 0 is entered.
- Inside the loop, it prompts the user to input a number (n) and calculates the sum of the first n prime numbers.
- The loop exits if the entered number is 0.

**Flowchart:**

**Python Code Editor:**

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**Previous:** Write a Python program to find the difference between the largest integer and the smallest integer which are created by 8 numbers from 0 to 9. The number that can be rearranged shall start with 0 as in 00135668.

**Next:** Write a Python program that accept a even number (>=4, Goldbach number) from the user and create a combinations that express the given number as a sum of two prime numbers. Print the number of combinations.

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