Are numbers greater than one plural? [duplicate]

Two apples are plural.

When I refer to a number of items only by their count, is the count singular?

For example: "Two is enough."

Is that correct?

Looking a this Google Ngram, it seems that both is and are are valid.

And having a look through the excerpts from the books, I tend to agree that authors use either.

Some examples:

• "is enough"

We use the pigeonhole principle to conclude that three is enough.

— A Logical Approach to Discrete Math - Page 356

Every one of my cymbals is also a crash cymhal. I only use three. Three is enough.

— The Drummer's Time: Conversations with the Great Drummers of Jazz

They say three is enough, thereby not attracting the folks from Chicago, Aurora, Fox River Valley.

— The Quality Health-Care Coalition Act of 1998

• "are enough"

Or there may be four sisters, but three are enough to present the full range of good and evil.

— Old Tales and New Truths: Charting the Bright-Shadow World

Three are enough for most anything.

— Yachting - Jan 1987 - Page 64

The throat is the most common, and perilous, location for the hooks to hang up, because even two of the three are enough to block that passageway and doom the luckless gamefish to starvation.

— Field & Stream - Mar 1989 - Page 68

So, in conclusion, you can treat the bare number as either plural or singular.