Question

Prompt the user for a positive whole number (call it n)

Use a loop to calculate the following:

Sum: 1+2+...+n

Sum of squares: 1^2 + 2^2 + ... + n^2

factorial: 1 x 2 x ... x n

Print out the numbers when the loop is done.

Do this with a for loop and a while loop.

Call the class LoopArithmetic

Sample output:

The sum from 1 up to 5 is: 15

The sum of squares 1 to 5 is: 55

The factorial of 5 is: 120

Provide output for at least 3 different numbers.

Answer 1

import java.util.Scanner;

public class LoopArithmetic {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        System.out.print("Enter a positive integer: ");
        int n = in.nextInt();
        int sum = 0, sumSquares = 0, factorial = 1, j = 1;
        for (int i = 1; i <= n; i++) {
            sum += i;
            sumSquares += i * i;
        }
        while (j <= n) {
            factorial *= j;
            j++;
        }
        System.out.println("The sum from 1 up to " + n + " is: " + sum);
        System.out.println("The sum of squares 1 to " + n + " is: " + sumSquares);
        System.out.println("The factorial of " + n + " is: " + factorial);
    }
}