Use turbo (shift & click flag) to visualize pi in terms of the ratio of a circle area to square area. By calculating the ratio of relative areas, we get a a rough estimate of pi. Tiny purple dots line up in a grid to fill the space. We count how many fall within square and circle. Because the ratio of square area to circle area is pi/4, we calculate pi as: 4 X number of dots on circle / number of dots on square. We also calculate pi as circle dots / radius squared.
As the purple pen sprite moves over the grid it knows if it is touching the circle, square (or both), and it keeps count. The counts are very sensitive to the size of the circle relative to the square. They should have exactly the same width or else the pi estimate will be off (as is this one).
