Automorphic_Number.java

// In this section, we will learn automorphic numbers with examples and also
// create Java programs that check whether the number is automorphic or not.

// What is an automorphic number?
// A number is called an automorphic number if and only if the square of the
// given number ends with the same number itself. For example, 25, 76 are
// automorphic numbers because their square is 625 and 5776, respectively and
// the last two digits of the square represent the number itself. Some other
// automorphic numbers are 5, 6, 36, 890625, etc.

class Automorphic_Number {
    // user-defined static method that checks whether the number is automorphic or
    // not
    static boolean isAutomorphic(int num) {
        // determines the square of the specified number
        int square = num * num;
        // comparing the digits until the number becomes 0
        while (num > 0) {
            // find the remainder (last digit) of the variable num and square and comparing
            // them
            if (num % 10 != square % 10)
                // returns false if digits are not equal
                return false;
            // reduce num and square by dividing them by 10
            num = num / 10;
            square = square / 10;
        }
        return true;
    }

    // Driver code
    public static void main(String args[]) {
        // number to be check
        // calling the method and prints the result accordingly
        System.out.println(isAutomorphic(76) ? "Automorphic" : "Not Automorphic");
        System.out.println(isAutomorphic(13) ? "Automorphic" : "Not Automorphic");
    }
}