Python summation from 1 to n or (sum of series 1+2+3+4+….+n in python)

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Computing the summation of all the numbers from 1 to n is a common task in programming, and there are multiple ways to do it in Python. In this article, we will explore two approaches: using a loop and using a mathematical formula.

sum of n numbers in python using for loop

One way to compute the summation is to use a loop. This approach involves iterating over the numbers from 1 to n and adding each number to a result variable. Here’s an example of how to do this:

def sum_from_1_to_n(n):
    result = 0
    for i in range(1, n + 1):
        result += i
    return result

print(sum_from_1_to_n(5))  # Output: 15 (1 + 2 + 3 + 4 + 5)
print(sum_from_1_to_n(10))  # Output: 55 (1 + 2 + 3 + ... + 10)

In the above example, we define the sum_from_1_to_n() function that takes an integer n as an argument and returns the summation of all the numbers from 1 to n. The function initializes a variable result to 0 and uses a for loop to iterate over the numbers from 1 to n, adding each number to result. After the loop, the function returns the result

sum of n numbers in python using mathematical formula

Another way to compute the summation is to use a mathematical formula. This approach involves using a formula that takes n as an input and returns the summation of all the numbers from 1 to n. Here’s an example of how to do this:

def sum_from_1_to_n(n):
    return (n * (n + 1)) // 2

print(sum_from_1_to_n(5))  # Output: 15 (1 + 2 + 3 + 4 + 5)
print(sum_from_1_to_n(10))  # Output: 55 (1 + 2 + 3 + ... + 10)

In the above example, we define the sum_from_1_to_n() function that takes an integer n as an argument and returns the summation of all the numbers from 1 to n using the mathematical formula. Then, we call the function with different inputs and print the expected output for each test case.

sum of n numbers using while loop in python

To compute the summation of all the numbers from 1 to n in Python using a while loop, you can iterate over the numbers and add them to a result variable. Here’s an example of how to do this:

def sum_from_1_to_n(n):
    result = 0
    i = 1
    while i <= n:
        result += i
        i += 1
    return result

print(sum_from_1_to_n(5))  # Output: 15 (1 + 2 + 3 + 4 + 5)
print(sum_from_1_to_n(10))  # Output: 55 (1 + 2 + 3 + ... + 10)

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