Wrong why explain please

Question

import java.util.Scanner;
public class Javac {
public static void main(String[] args)
{
Scanner sc= new Scanner(System.in);
int num=sc.nextInt();

System.out.print(convert(num));
}
public static int convert(int num)
{
int dec=0;
int i=0;
while(num>0)
{
int temp=num%10; //
dec+=(temp*Math.pow(2, i));
num=num/10;
i++;
}

return dec;
}
}
// if i write like this
//dec=dec+(temp*Math.pow(2, i));
//why is not work
//

Answer 1

It is working fine. In terms of syntax