The topic is an article saying "Precision studies of antihydrogen atoms, for example, have shown that their characteristics are identical to hydrogen atoms to beyond the billionth decimal place." This suggest the "characteristic" is some kind of physical property that can be measured and compared.
Well, we all know that "the billionth decimal place" is an error. Nevertheless, my point was that far larger numbers can be related to physical things.
According to Stirling's approximation, (10^185)! is more than 10^10^187, which makes a billion decimal places look very small indeed.