Question

How to delete the first digit from a number in Java

Answer 1

public class MyClass {
    public static void main(String args[]) {
      int n = 87315;
      
      System.out.println((int)Math.log10(n));
      System.out.println((int)Math.pow(10, (int)Math.log10(n)));
        
      n = n % (int)Math.pow(10, (int)Math.log10(n));

      System.out.println(n);
    }
}


/*
run:

4
10000
7315

*/

 

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Answer 2

public class MyClass {
    public static void main(String args[]) {
      int n = 87315;
      
      String s = Integer.toString(n);
      n = Integer.parseInt(s.substring(1));
        
      System.out.println(n);
    }
}


/*
run:

7315

*/

 

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Answer 3

public class MyClass {
    public static void main(String args[]) {
      int n = 87315;
      
      n = Integer.parseInt(Integer.toString(n).substring(1));
        
      System.out.println(n);
    }
}



/*
run:

7315

*/

 

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Answer 4

public class MyClass {
    private static int remove_first_digit(int num) {
    	int total = (int)Math.log10(num); // total - 1 = 6
    
    	int first_digit = num / (int)Math.pow(10, (total));
    
    	return num - first_digit * (int)Math.pow(10, (total));
    }
    
    public static void main(String args[]) {
      	int n = 8405796;

	    n = remove_first_digit(n);

	    System.out.print(n);
    }
}





/*
run:
     
405796
    
*/

 

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