How would you say "There are 7 billion people in the world." (US/UK short scale) or "There are 7 thousand million people in the world." (European long scale), in both Esperanto and Ido?
I think in Esperanto it's supposed to be "Estas sep miliardoj da homoj en la mondo." In other words, words like "miliono", "miliardo", "biliono", "biliardo" are collective nouns that require the preposition "da". Contrast this with all numbers less than a million, which are cardinal adjectives not requiring "da" and admitting to agglutination rules. For instance, you can say "Estas sepmil homoj en tiu vilagxo." I'm pretty sure that's correct, but do I have it right?
In Ido, I'm not so sure, because I can't find any actual usage examples. Dictionaries show them as "miliono", etc., but the original manual by Beaufront listed them with the other roots as "milion", "bilion", etc. That seems to imply that you should be able to use the same combining rules as for smaller numbers. So just as you can say "Esas sepamil homi en ta vilajo", you should be able to say "Esas sepamiliard homi en la mondo". But is it supposed to be "Esas sep miliardi de homi en la mondo" instead?