Decimal to Binary

#1

why we take reminder first.

public class Decimal_To_Binary {
public static void main(String[] args) {
int n=43;
int ans=0;
int mul=1;
while(n!=0)
{
int rem=n%2;
ans=ans+remmul;
mul=10;
n=n/2;
}
System.out.println(ans);
}
}