Two solutions-----Judging whether a number is a conservative number

What is a conservative number? Let’s first understand:


According to this requirement, write the code as follows.
Solution 1: According to the definition of a conservative number, judge whether the low digit of the squared result is equal to the original number.

package Num;
/*
* 判断一个数是不是守形数
* */
import java.util.Scanner;
public class Main{
    
    
    public static void main(String[] args){
    
    
        Scanner sc=new Scanner(System.in);
        while(sc.hasNext()){
    
    
            String num=sc.nextLine();
            isNum(num);
        }
    }

    public static void isNum(String num){
    
    
        int n=Integer.parseInt(num);
        int s=(int)Math.pow(n,2);
        String s1=Integer.toString(s);
        if((s1).endsWith(num)){
    
    
            System.out.println("Yes!");
        }else{
    
    
            System.out.println("No!");
        }
    }
}

Solution 2: Record the number of digits n, so that the number obtained by squaring num%10^n, if the result obtained is the same as n, it is a conservative number.
code show as below:

import java.util.Scanner;
public class Main{
    
    
    public static void main(String[] args){
    
    
        Scanner sc=new Scanner(System.in);
        while(sc.hasNext()){
    
    
            String num=sc.nextLine();
            isNum1(num);
        }
    }
    public static void isNum1(String num){
    
    
        int len=num.length();
        int n=Integer.parseInt(num);
        int n1=(int)Math.pow(n,2);
        if(n1%Math.pow(10,len)==n){
    
    
            System.out.println("Yes!");
        }else {
    
    
            System.out.println("No!");
        }
    }
}

Which method do you prefer?