Example: Sum of First n Odd Numbers (Formula) in C++

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// Sum of First n Odd Numbers (Formula)
#include <iostream>
#include <cmath> // Required for pow() function, though n*n is simpler
using namespace std;

int main() {
    // Step 1: Declare variables for number of terms and sum
    int n_terms;
    long long sum; // No need to initialize sum here, calculated directly

    // Step 2: Prompt user for input
    cout << "Enter the number of odd terms to sum: ";
    cin >> n_terms;

    // Step 3: Input validation
    if (n_terms <= 0) {
        cout << "Number of terms must be positive." << endl;
        return 1;
    }

    // Step 4: Calculate the sum using the formula
    sum = static_cast<long long>(n_terms) * n_terms; // Sum of first n odd numbers is n*n

    // Step 5: Display the result
    cout << "Sum of the first " << n_terms << " odd numbers is: " << sum << endl;

    return 0;
}