She saw right away that the additional tiles that you had to add around the edges was always going to grow by two, so she was very confident about how she made those numbers there.
Also sah sie sofort, daß die zusätzlichen Plättchen, die man an die Kanten anlegen mußte, immer um zwei anwuchsen. Sie war sich also sehr sicher, wie sie zu diesen Zahlen gekommen war.