import java.util.Scanner;

public class counting {

	public static void main(String[] args) {
		
		Scanner in = new Scanner(System.in);
		
		int t = in.nextInt();
		while (t --> 0) {
			long n = in.nextLong(), s = in.nextLong();
			long ans = n % s, div = n / s;
			
			while (div > 0) {
				ans += div % 10;
				div /= 10;
			}
			
			System.out.println(ans);
		}
		
		in.close();
	}
}