What are square and triangle numbers?
If you are given n tiles and you can form a perfect figure with them, then n belongs to the family of figurate or polygonal numbers. Square and triangle numbers are the most common sets of figurate numbers, but there are pentagonal, hexagonal, heptagonal, et cetera. • Square numbers The nth square number, sn = n² • Triangle numbers The nth triangle number, tn = ½n(n + 1). They appear in many familiar contexts. Think about the shape and the number of pins in the game 10-pin bowling, or the way in which the fifteen red balls in a game of snooker are placed.
