10 cubits with a circumference of 30 cubits, yadda yadda yadda
edit: oh holy shit I hadn't thought about this kerfuffle for 25 years but when I made this comment I went looking on the "internet" and holy shit the apology I found is insane. Absolutely in.sane.
Really, go look at the apologists trying to say that atheists don't know what they are talking about, that the measurements aren't precise, that there is a 4 inch rim that makes up for the difference. Just. Wow. Fucking WOW.
Any religious fucker that wants to @ me, bring it to my DMs. If you defend this bullshit about 10/30 cubits fucking bring it.