Do you know what makes a number triangular? The fifth grade students in Mrs. Haseltine’s math class also found out that some numbers are pentagonal, hexagonal and even pyramidal! Numbers can be classified as deficient, perfect or abundant. Some numbers are said to be powerful, while others are square-free, and every number is either odious or evil. View the gallery to see examples of the properties the students discovered. Learn facts about your favorite numbers at Zoo of Numbers and Number Gossip.