Sum of Integers

Sum of Integers

Calculate sum of integers from 1 to given N (including).

example

Input: Integer (int).

Output: Integer (int).

Examples:

assert sum_upto_n(1) == 1
assert sum_upto_n(2) == 3
assert sum_upto_n(3) == 6
assert sum_upto_n(4) == 10

How it’s used: this function can be used in a variety of mathematical and algorithmic contexts, such as in calculating the nth triangular number, determining the cost for certain operations in algorithms, etc.

Precondition:

  • 1 ≤ N ≤ 900.