This is why you should read the bible.
Pi (the ratio of the circumference to the diameter of a circle) is really not given in the Bible. There is a pair of references that seem at first glance to indicate that this value is 3, but a closer reading shows that it really doesn't.
Now he made the sea of cast metal ten cubits from brim to brim, circular in form, and its height was five cubits, and thirty cubits in circumference. Under its brim gourds went around encircling it ten to a cubit, completely surrounding the sea; the gourds were in two rows, cast with the rest. It stood on twelve oxen, three facing north, three facing west, three facing south, and three facing east; and the sea was set on top of them, and all their rear parts turned inward. It was a handbreadth thick, and its brim was made like the brim of a cup, as a lily blossom; it could hold two thousand baths. - 1 Kings 7:23-26 (NASB)
2 Chronicles 4:2-5 is similar, describing the same temple furnishing. Since the "sea" was flared "like a lily blossom", the diameter measurement was made "from brim to brim," but the circumference measurement was probably a direct measurement made below the flared brim. If you paid attention in geometry class, you could compute the amount of the flare of the brim to be about (10-(30/3.1416 ))/2 = 0.225 cubits (about a handbreadth) on each side. Construction of a scale model using these dimensions and description is left as an exercise for the reader.