1 Kings 7:23 And he made a molten sea, ten cubits from the one brim to the other: it was round all about, and his height was five cubits: and a line of thirty cubits did compass it round about. (see also 2 Chron. 4:2)

This is a very old chestnut that complains that the measurements given for the circular bath do not give a proper value for pi. There are a couple of answers to this, one of which we give a link to below, and which is better than the one I have here. The more common answer is that these verses give an estimate of pi that is rounded to the nearest full digit. Interestingly it was a skeptic who, in the 153rd issue of the Biblical Errancy newsletter, issued this criticism:

I can say that it must be 31.4159265...cubits, not 31.4. We all make an agreement to round to a certain place. Remembering that the circumference was not necessarily a calculation, but an observation, probably done by using a forearm as a ruler, it would be logical to round to the nearest cubit. Any diameter from 9.5 cubits to 10.5 cubits would round to 10 cubits.... The reportage would be correct, rounded to the nearest unit.... in the days when basins were measured by forearms, the nearest cubit was as good reporting as you could get, and in the case of the above-mentioned possible "precise" measurements, can indeed be an accurate representation of what was there.

McKinsey's reply to this was quite interesting. We'll consider it in pieces:

First, the fact is that 30 cubits is not the correct answer. If you say that 31.4 is not the correct answer either, then I will allege that your 31.4159265 figure is incorrect as well. Following the stream of logic you have set in motion, there is no correct answer, because every answer involves rounding. Any answer would be automatically false.

Of course there is a certain category error here, since the value of pi is (so we are told by the mathematicians) one of those things that we can never provide the "correct" answer for -- it goes on an on and on. So the 1 Kings writer would have either had to estimate or else he would still be writing today.

Second, you are assuming the answer involves rounding without proving as much. The answer is wrong until you can prove it results from rounding. You can't allege it's the result of rounding until I prove it's not.

McKinsey goes on to blather for several additional sentences in this vein, but it is well-known and accepted that ancient estimates of distance, length, etc. were not always given down to the levels of our modern measurements (though see below). His only other comment in this regard is:

If guesswork is going to be admissible, then many biblical contradictions could be explained away by mere conjecture and theorizing. Nearly every numerical contradiction in the OT, for example, could be lightly dismissed by simple reference to the "rounding" defense.

As we have just noted, however, the "pi" category is of a rather different nature, and rounding was standard procedure in the ancient world. It therefore behooves McKinsey to fulfill the burden of proof in this matter. It is merely skeptical chauvanism to proclaim, as our subject does: "Round numbers or not, the number is incorrect period. What difference does the culture make?" It is significant that our subject finds it necessary to dip into the similarly oblivious work of Harold Lindsell, who is just as disdainful of reading the Bible in its context as our subject is (and who also makes the same category error of equating an estimation of an amount equal to pi with the simple formula of 2+2).

Amateur skeptic Scott Bidstrup has elaborated upon this objection a bit. He writes:

I don't expect perfect mathematics, but accuracy to at least two orders of magnitude, which the ancients understood and depended on themselves, isn't unreasonable.

Bidstrup is not telling everything here. The ancients did measure pi more precisely in some cases -- but this is found in places like the Rhynd Papyrus, a book of mathematical equations. The Kings and Chronicles writers were evidently literate, but there is no evidence that they were mathematicians. We would rightly expect accuracy of greater order from specialists in mathematics like the writer of the Rhynd Papyrus, and from Babylonian astrologers. But such an expectation is ludicrous from a non-mathematician.

Put it this way: If we ask how many gallons of fuel a rocket contains, we expect a detailed answer like "4,942,827.78 gallons" from a NASA engineer, if he is involved in a techincal discussion with other engineers. If he's talking to the press, and he is savvy, he'll say "4.9 million gallons" rather than bewilder the scientifically inert with more detail. Your average hobbyist (or even a reporter) will say "5 million gallons". Are any of them incorrect? No, because there is a semantic contract that correlates the level of precision with the level of expertise. Unless the Bible authors were mathematicians on the level of Archimedes (one of the other few ancients to go this far in looking at pi), then it is ridiculous to expect precision to that level from them.

For more info, here are some interesting sites:

http://www.geocities.com/EnchantedForest/5815/history.html

For another answer, which neither McKinsey nor Bidstrup know about, check here.

And now here's a funny update. Apparently our old pal Sam Gibson needed some help, so he wrote in to "Dr. Math" and the results of the correspondence are here. Sam gets hit pretty hard by the good Dr. Math! (On his own site, Sam argues that rounding off pi equates with "rounding off" books of the Bible and taking, say, Romans 7 out of Romans! Sam still can't tell apples from oranges!)

A helpful reader has also made this point:

The Hebrew Rabbi and writer of the earliest known Hebrew geometry textbook (Mishnat ha-Middot,) Nehemiah, states, "Now it is written: And he made the molten sea of ten cubits from brim to brim, round in compass, and yet its circumference is thirty cubits, for it is written: And a line of thirty cubits did compass it round about. What is the meaning of the verse, And a line of thirty cubits, and so forth? Nehemiah says: Since the people of the world say that the circumference of a circle contains three times and one seventh of the thread, take off that one seventh for the thickness of the walls of the sea on the two brims, then there remain, Thirty cubits did compass it round about." As you quaintly termed them, amateur skeptics make great pet parrots. (This could be said of either side, rather unfortunately.) And for those that hate estimates so much, the fact is that this wasn't a perfect circle, (something that doesn't exist in the real world,) so pi, per se, isn't being measured anyway.

And another has added:

One answer I would give to this embarrassing (to me) guy, would be that maybe the circumference actually measured 30.3l213 cubits and the diameter measured 9.64866 cubits. The ancients who perhaps hated fractions as much as school kiddies do today, simply gave the numbers as 30 and 10 respectively. Why should they not? We do know that they were not into the precision fetish that we are today. Also, if the Bible had to go into as much detail as guys like HiFaultin' Sammy want, I hardly would be carrying it to church. I'd need a wheelbarrow.