This afghan demonstrates where triangular numbers and square numbers coincide. A triangular number is the result of adding counting numbers. A square number is the result of multiplying a number by itself.
Triangular: 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 = 36
Square: 6 x 6 = 36
The answers in this example coincide.
The afghan shows where the 49th triangular number and 35th square number coincide, giving 1225 small squares.