In this shot, we will learn how to check whether or not a number is automorphic. An automorphic number is a number whose square ends with the same digits as the number itself.
For example, 25 and 76 are automorphic numbers because their squares are 625 and 5776, respectively. The square’s last two digits represent the number itself. Other automorphic numbers are 5, 6, 36, 890625, and so on.
If we take 35 or 20 as input, we will see that the squares of these numbers, i.e., 1225 and 400, do not contain 35 or 20 at the end. So these numbers are not automorphic.
We can follow the solution approach described below.
We will create an isAutomorphic()
function which takes the square of the number and the number as input and returns true
if the number is automorphic. Otherwise, it returns false
.
Let’s look at the code now.
To test, input a number in the input box.
import java.util.Scanner; class Automorphic { public static void main(String[] args) { Scanner sc= new Scanner (System.in); int number= sc.nextInt(); int sqr= number*number; //check whether the last digits of square are matched // with the number itself if(isAutomorphic(sqr,number)) System.out.println(number + " is an automorphic number"); else System.out.println(number + " is not an automorphic number"); } static boolean isAutomorphic(int square, int number){ while(number >0){ if(square%10!=number%10) return false; square/=10; number/=10; } return true; } }
Enter the input below
In the first line of code, we imported the java.util.Scanner
class to read input from the user.
In line 6, inside the main function, we take the number from the user by creating Scanner
object and store that input in an integer number
In line 7, we calculate the square of that number and store it in a variable sqr
of integer type.
Assume that the square of that number is not more than
Integer.MAX_VALUE
in Java.
In line 9, we call the isAutomorphic()
function. If it returns true
then we print that the number is automorphic. Otherwise we do not.
From lines 17 to 27, we define the isAutomorphic()
function. In this function, we run a while loop till the number is greater than 0. Then we compare the last digit of both squares of the number and the number itself, respectively. If they are not equal, we return false
. Otherwise, we return true
.
In this way, we can check whether a number is automorphic or not.
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