Then some argue that the exact value is indeed an integer as well. It is defined as the number of carbon atoms in exactly 12 grammes of a certain carbon isotope. And then one may ask whether we are speaking of whole atoms or if we allow “partial atoms” to fill up our 12 grammes.

I can’t imagine anyone calculating anything with that kind of accuracy anyway, so it doesn’t matter so much.

also, the answer to the introductory riddle (”Isn’t it unusual that there are words that represent numbers, but not numbers that represent words?”) is that speech is primary to writing. in other words, that claim has it backwards – the word “eight” does not represent “8″; rather, “8″ represents “eight.” the names for numbers are words even if they were never written down as numerals. having numbers represent words would be pretty bizarre because our writing generally mirrors our spoken language, not the other way around.