# Double zero, double zeros or double zeroes?

What's the correct way to refer to two consecutive digits `0`?

• double zero?
• double zeros?
• double zeroes?

Here's an example phrase:

The number ends with double zero[es].

In this case, "double zero" is a singular noun referring to two zeros. So you'd say:

There's a double zero.

If you're referring to multiple zeros in plural, you'd use "zeros":

There are two zeros.

Zeroes is a verb meaning to adjust to zero. For example, taring a scale:

I zeroed the scale.

He zeroes the scale.

• Interestingly, the verb usage you are describing seems to be much less common than the (derived?) phrase "zero in [on]", typically meaning to aim a weapon on a target, to narrow down a search, or (more recently, it seems) to converge on some consensus. books.google.com/ngrams/… (I tried to select sensitive and specific ngrams. Some disqualified candidates: "to zero", "zero in", "to zero in", "zero the", "zeroes") Feb 17, 2021 at 11:03

The others nailed the reasoning, but just for extra evidence, Google Ngrams confirms that "double zero" is the most commonly-used option: Interestingly "double zeros" seems to had a brief popularity spike around the 1950s where it tied with "double zero".

• "two zeros" shows even more use than "double zero". Jul 10, 2015 at 20:45
• I left that out because it could be used in more contexts than the "double" family. (I would guess the spike after WWII in the "two zeros" graph is larger than the rest at least partially because of Japanese Zero fighter planes) Jul 13, 2015 at 22:43
• Note that in the mathematics of linear control theory, a "double zero" (or, perhaps more commonly, "double root") is a polynomial root which occurs twice as factor in the numerator of a transfer function. E.g., if the transfer function is (s^3 - 2*s^2 + s)/(s+2) = s*(s-1)^2/(s+2), then s=1 is a double zero/root. "Double zeros" is the occurrence of such roots, of which there may be several. I am mentioning this to justify another, arguably legitimate, use of "double zeros", which may have had a spike after WW2 and in the Cold War. Feb 17, 2021 at 10:00
• PS: Check out en.wikipedia.org/wiki/Control_theory#History "By World War II, control theory was becoming an important area of research." ... "The Space Race also depended on accurate spacecraft control,". Even though control theory has progressed a lot beyond LTI systems with simple transfer functions representable by polynomial fractions, the simple mathematical models are still important for simple systems, subsystems, computational simulations where the complexity of interaction between many components is more important than the accuracy of each component model, etc.. Feb 17, 2021 at 10:28