“In its natural state, uranium has 238 atoms and is thus called U-238. Fissile uranium—the stuff that can make an atom bomb—has 235; therefore, it’s called U-235. The process of enrichment is done with gas centrifuges, which, by spinning very rapidly, separate the heavier U-238 isotopes from the lighter U-235 ones.
“About 0.7 percent of U-238 is naturally fissile.”
—excerpt from footnote to “Jaw-Jaw With Iran” on Slate website.
I know, it’s not hard to figure out what he means; in fact, I might have missed the errors altogether if I had been just scanning the article. But they are so elementary, and clearly not typos, that they do make me wonder, what else does the guy not know?