# “How many billion” or “How many billions”?

I know that we have to use a plural noun after How many, and I also know that we have to say "five billion dollars", not "five billions dollars" (OALD)

So why does the writer write like this:

Here’s How Many Billions Evan Spiegel Has Lost Since Snap’s IPO
(Fortune)

• When a quantifier comes before it, and a noun comes after it, "billion" is an unmarked plural, i.e. it has no plural form. "Billion" as used as in the headline, though, without a following noun (and also when followed by of) is a countable noun with a normal plural form, like score or dozen. "He lost billions of dollars", and "He lost billions", but "He lost five billion dollars". – P. E. Dant Reinstate Monica Jul 13 '17 at 16:38
• @P.E.Dant - I would suggest that you propose your comment as an answer. – Jeff Zeitlin Jul 13 '17 at 19:23
• @P.E.Dant: If so, what is the singular form of "billions"? – haile Jul 14 '17 at 5:09
• The singular, to no-one's surprise, is "billion"! "I lost a billion [dollars]!" (Just like "I'll have a dozen.") Have you consulted any of the dozens of good English dictionaries on the subject? Most of them include a very clear explanation of the usage, and far superior to what I can squeeze into a comment. – P. E. Dant Reinstate Monica Jul 14 '17 at 5:12
• @P.E.Dant: I disagree, because when you say "I lost a billion [dollars]!", "billion" is NOT a noun, but a modifier/quantifier/adjective. – haile Jul 14 '17 at 5:19

How many billion or how many billions?

Both are grammatical, but the latter is far more common and idiomatic.

You usually use hundred, thousand, million, billion, or trillion with a final 's' after the determiner "many" if there's no noun after these numbers. For examples:

How many billions did he lose?

But if there's a noun after these numbers, you use them without final 's'. For example:

How many billion dollars did he lose?

Further, you use these numbers without 's' after a, one,two, three, a few several, etc. For examples:

A/one hundred dollars, six thousand people, several billion dollars, etc.

Also, ou use these numbers with a final 's' if there's no other number before them but there's the preposition "of" after them. For examples:

Hundreds of dollars, millions of people,etc.

• "How many billions?" is idiomatic in BrE, but the majority of English speakers use "How many billion?". – P. E. Dant Reinstate Monica Jul 14 '17 at 17:19
• books.google.com/ngrams/… – Khan Jul 14 '17 at 19:09
• The ngram is meaningless. You have formed a faulty pair of comparands. Take a look at the citations for "how many billion". The majority are of the form "How many billion dollars more did..." The plural form would never be used in this context. (Note the question mark in the examples in my comment.) – P. E. Dant Reinstate Monica Jul 14 '17 at 19:22

When billion is an adjective, you can't pluralize it. When it is a noun, it must be. Here's how many billions--billions is a noun 5 billion dollars--billion is an adjective of dollars. Dollars is pluralized. It is no different than saying two dollars.

Both are correct. A number word can be used as an adjective or a noun. You choose depending on what you are intending to emphasize -- the billion as a unit or the thing you are counting. You can also use the phrase "billions of x" to show a large quantity.

• Use the noun "billions" if you want to talk about it as a unit. "there are many billions in a googolplex." (the billion is a single unit)
• Use the adjective "billion" if you are using it to describe a countable noun. "I have ten billion dollars." "I have baked a billion cookies." (I am talking about an actual amount)

• "there are billions of stars in the sky." (so many that they can't be counted.)

In American English, we say "2 billion". In British English, they say "2 billions".

Americans will say "billions" when it is more than one billion but we don't give the number. For example, "There are 100 billion stars in the Milky Way" -- singular because I gave a number of how many billion. But, "There are billions of stars in the Milky Way" -- more than one billion but I'm not specifying how many. If I wanted to say there was one billion, I could say, "There are 1 billion stars", or more vaguely, "There are a billion stars".