private static final Scanner SCANNER = new Scanner(System.in);

public static void main(String[] args) {

int testCases = SCANNER.nextInt();

while (testCases-- > 0) {

final int n = SCANNER.nextInt();

final int m = SCANNER.nextInt();

final int rows = ceil((double) (n - m + 1) / m) + 1;

final int k = m - ((n - m + 1) % m);

System.out.println(summation(m - 1) * rows - (summation(m - 1) - summation(m - k - 1)));

}

}

private static int ceil(double x) {

return (int) Math.ceil(x);

}

private static long summation(long x) {

return (x * (x + 1)) / 2;

}