In the following sentence:

Нас миллиарды на земле.

Source: https://forum.duolingo.com/comment/30984756

Why is this accusative or genitive, not nominative? The sentence is translated into English "We are billions on the Earth.".

In the following sentence:

Нас миллиарды на земле.

Source: https://forum.duolingo.com/comment/30984756

Why is this accusative or genitive, not nominative? The sentence is translated into English "We are billions on the Earth.".

I found another example:

Их сотни миллионов.