Chapter 26 Question 26 (Palindromic prime)

Chapter 26 Question 26 (Palindromic prime)

• **6.26 (Palindrome prime number) A palindrome prime number means that a number is both a prime number and a palindrome number. For example: 131 is a prime number, but also a palindrome prime number. The same goes for mathematics 313 and 757. Write a program to display the first 100 palindrome prime numbers. Each line displays 10 numbers, separated by a space. As shown below:
  2 3 5 7 11 101 131 151 181 191
  313 353 373 383 727 757 787 797 919 929
  …
  **6.26(Palindromic prime) A palindromic prime is a prime number and also palindromic. For example, 131 is a prime and also a palindromic prime, as are 313 and 757. Write a program that displays the first 120 palindromic prime numbers. Display 10 numbers per line, separated by exactly one space, as follows:
  2 3 5 7 11 101 131 151 181 191
  313 353 373 383 727 757 787 797 919 929
  …
• Reference Code:

package chapter06;

public class Code_26 {
    
    
    public static void main(String[] args) {
    
    
        int palindPrimeCount = 0;
        for(int i = 2;palindPrimeCount != 100;i++) {
    
    
            if(isPalindrome(i) && isPrime(i)) {
    
    
                System.out.print(i+" ");
                palindPrimeCount++;
                if(palindPrimeCount % 10 == 0)
                    System.out.print("\n");
            }
        }
    }
    public static int reverse(int number) {
    
    
        int reverseNumber = 0;
        do {
    
    
            reverseNumber = reverseNumber * 10 + number % 10;
            number /= 10;
        }while(number > 0);

        return reverseNumber;
    }
    public static boolean isPalindrome(int number) {
    
    
        return reverse(number) == number;
    }
    public static boolean isPrime(int number) {
    
    
        for(int i = 2;i <= Math.sqrt(number);i++)
            if(number % i == 0)
                return false;
        return true;
    }
}

• The results show that:

2 3 5 7 11 101 131 151 181 191 
313 353 373 383 727 757 787 797 919 929 
10301 10501 10601 11311 11411 12421 12721 12821 13331 13831 
13931 14341 14741 15451 15551 16061 16361 16561 16661 17471 
17971 18181 18481 19391 19891 19991 30103 30203 30403 30703 
30803 31013 31513 32323 32423 33533 34543 34843 35053 35153 
35353 35753 36263 36563 37273 37573 38083 38183 38783 39293 
70207 70507 70607 71317 71917 72227 72727 73037 73237 73637 
74047 74747 75557 76367 76667 77377 77477 77977 78487 78787 
78887 79397 79697 79997 90709 91019 93139 93239 93739 94049 

Process finished with exit code 0