Question

in java

Use a for loop and nested if statements to determine if a number is even or prime

Use the numbers 30 to 60

Hint: you may need to review what is a prime number

Output:

30 . . . even

31 . . . prime number

32 . . . even

33 . . .

34 . . . even

35 . . .

36 . . . even

37 . . . prime number

etc.

Answer 1

package test.java;

public class TestPrime {
  
   public static void main(String[] args){
       int startNumber = 30;
       int endNumber = 60;
       boolean isNonPrime = false;
       for(int i = startNumber; i<=endNumber; i++){ //This will loop from 30 to 60
           if(i==2){ //As 2 is the only even prime number;though will nnot be needed in this case, just used to keep up with prime number logic
               System.out.println(i+"...prime number");
           }else if(i%2==0){//This will check if the number is even i.e divisibility by 2
               System.out.println(i+"...even");
           }else{
               isNonPrime = false;
               /* Check prime number by checking if the number has any factor from 2 to (number/2)
               * e.g if the number is 39, it will divide 39 starting from 2 to 39/2 = 19 to check if any number divides 39
               * If no number divides that means the number is prime else it is non prime*/
               for(int k = 2; k<=i/2;k++){
                   if(i%k==0){
                       isNonPrime = true;
                       break;//breaking out of the loop as we already found a factor for the number indicating it is a non prime number
                   }
               }
              
               if(isNonPrime){
                   System.out.println(i+"...");
               }else{
                   System.out.println(i+"...prime number");
               }
           }
       }
   }

}

Explanation:

Comments are given within the code . The check for prime number for 2 has also been given in the code , however that will not be need in our case as we are iterating through number 30 to 60.

The program output will be like below:

30...even
31...prime number
32...even
33...
34...even
35...
36...even
37...prime number
38...even
39...
40...even
41...prime number
42...even
43...prime number
44...even
45...
46...even
47...prime number
48...even
49...
50...even
51...
52...even
53...prime number
54...even
55...
56...even
57...
58...even
59...prime number
60...even