// Miya Natsuhara
// 07-12-2019
// CSE142
// TA: Grace Hopper

// Given a number from the user, prints out different mathematical properties and facts about that 
// number. 

import java.util.*;

public class FunWithNumbers {
   public static void main(String[] args) {
      Scanner console = new Scanner(System.in);
      System.out.print("Please type an integer: ");
      int num = console.nextInt();
      isZero(num);
      isEvenOrOdd(num);
      isPosOrNeg(num);
      getSmallPrimeFactors(num);
      System.out.println("sum of numbers from 1 to " + num + " is " + gaussSum(num));
   }

   // Prints out whether the given number is 0. 
   // int num: number to test
   public static void isZero(int num) {
      if (num == 0) {
         System.out.println("0 is zero!");
      }
   }
   
   // Prints out whether the given number is even or odd. 
   // int num: number to test
   public static void isEvenOrOdd(int num) {
      if (num % 2 == 0) {
         System.out.println(num + " is even!");
      } else {
         System.out.println(num + " is odd!");
      }
   }
   
   // Prints out whether the given number is positive or negative. 
   // int num: number to test
   public static void isPosOrNeg(int num) {
      if (num > 0) {
         System.out.println(num + " is positive!");
      } else if (num < 0) {
         System.out.println(num + " is negative!");
      }
   }
   
   // Prints out whether the small prime number (2,3,5,7) are factors of the given number.
   // int num: number whose factos will be looked at
   public static void getSmallPrimeFactors(int num) {
      if (num % 2 == 0) {
         System.out.println("2 is a factor of " + num);
      }
      if (num % 3 == 0) {
         System.out.println("3 is a factor of " + num);
      }
      if (num % 5 == 0) {
         System.out.println("5 is a factor of " + num);
      }
      if (num % 7 == 0) {
         System.out.println("7 is a factor of " + num);
      }
   }
   
   
   // Computes and returns the sum of all numbers up to and including the given number
   // int num: number whose value will be used to sum up to 
   public static int gaussSum(int num) {
      // NOTE: An example of a *cumulative algorithm* where we set up our result variable 
      //       outside of the loop, and then accumulate pieces of the result inside of the loop.
   
      // keep a running total
      // for every number 1 to the number 
      //       add in that number to the running total
      int runningTotal = 0; 
      for (int i = 1; i <= num; i++) {
         runningTotal = runningTotal + i;
      }
      return runningTotal;
   }
}