Ben C wrote: On 2007-11-01, Ben C <spamspam@spam.eggs> wrote: [...] A picometre is 4e-11 inches. So that's 1/100000000000th of an inch. Sorry-- 4/100000000000th of an inch (approximately). I found Leo's comments quite helpful. We humans are good with half an inch or a quarter of one, even a tenth. But -11 exponent is not easy to visualize if one doesn't work in that scale commonly