Which one of the followings is a triangular number?, 17, 16, 21, 28, 2, 5, Which of the following isn’t a triangular number?, 26, 27, 28, 21, 15, 10, What is the fifth triangular number?, 1, 3, 6, 10, 17, 15

Triangular numbers

Табло

Визуален стил

Опции

Шаблон за превключване

Възстановяване на авто-записаната: ?