Since the projected distance of the pinhole to the floor was 56cm, and the image was .5cm, then the ratio of the two is:
56/.5=112. But the average distance to the Sun is 149,600,000Km, then the diameter of the Sun is:
149,600,000/112=1.335 X 10^6Km, on this scale. The Sun's diameter is in fact: 1, 392,000Km. Close!.