In describing the large basin referred to as "a sea" that sat in front of Solomon's temple, I Kings 7:23 and II Chronicles 4:2 say that the diameter was 10 cubits from brim to brim and the circumference was 30 cubits. That would give a pi of 3, but pi is approximately 3.1416. This means the circumference should be almost 31½ cubits, not 30. Some might see this as a mistake.
Of course, since the lip on the brim was shaped like lily flowers, it is possible that the circumference was measured under the brim (or maybe under the gourd decoration under the brim) and the diameter of where the measurement was taken was less than 10 cubits. For that to be the case, the lip would have to extend outward almost a quarter of a cubit (.225) or about 4 inches, a cubit being between 17.5 and 18 inches. Surely the lily-flowered lip extended, but we are not told by how much.
While this is possible, it is also possible that the dimensions were recorded in round numbers. Thus, anything from 9.5 to 9.70 cubits in diameter yields 29.85 to 30.49 cubits around. A good median is 9.66 (which would be rounded to 10) cubits in diameter which results in a circumference of 30.35 (which would be rounded to 30) cubits.
Thus we see that there are a couple of ways to understand the dimensions given in the text without thinking that there is a mistake in the figures.
Bruce Terry