Numbers of Zeros in a Million, Billion, Trillion, and More

Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels.

Have you ever wondered how many zeroes are in a million?

Do you know how many zeros there are in a vigintillion?

Someday, you may need to know this for science or math class. Then again, you might just want to impress a friend or teacher.

Numbers Bigger Than a Trillion

The digit zero plays an important role as you count very large numbers. It helps track these multiples of 10 because the larger the number is, the more zeroes are needed. In the table below, the first column lists the name of the number, the second provides the number of zeros that follow the initial digit, and the third tells you how many groups of three zeros you would need to write out each number.

All of Those Zeroes

A table like the one above can certainly be helpful in listing the names of all of the numbers depending on how many zeros they have. But it can be really mind-boggling to see just what some of those numbers look like.

Below is a listing—including all the zeros—for the numbers up to decillion, a little more than half the numbers listed in the above table.

Ten: 10 (1 zero)
Hundred: 100 (2 zeros)
Thousand: 1000 (3 zeros)
Ten thousand 10,000 (4 zeros)
Hundred thousand 100,000 (5 zeros)
Million 1,000,000 (6 zeros)
Billion 1,000,000,000 (9 zeros)
Trillion 1,000,000,000,000 (12 zeros)
Quadrillion 1,000,000,000,000,000 (15 zeros)
Quintillion 1,000,000,000,000,000,000 (18 zeros)
Sextillion 1,000,000,000,000,000,000,000 (21 zeros)
Septillion 1,000,000,000,000,000,000,000,000 (24 zeros)
Octillion 1,000,000,000,000,000,000,000,000,000 (27 zeros)
Nonillion 1,000,000,000,000,000,000,000,000,000,000 (30 zeros)
Decillion 1,000,000,000,000,000,000,000,000,000,000,000 (33 zeros)

Zeros Grouped in Sets of 3

Reference to sets of zeros is reserved for groupings of three zeros, meaning they are not relevant for smaller numbers. We write numbers with commas separating sets of three zeros so that it's easier to read and understand the value. For example, you write one million as 1,000,000 rather than 1000000.

As another example, it's much easier to remember that a trillion is written with four sets of three zeros than it is to count out 12 separate zeroes. While you might think that that one is pretty simple, just wait until you have to count 27 zeros for an octillion or 303 zeros for a centillion.

It is then that you will be thankful that you only have to remember nine and 101 sets of zeros, respectively.

Numbers With Very Large Numbers of Zeros

The number googol (termed by Milton Sirotta) has 100 zeros after it. Here's what a googol looks like, including all of its required zeros:

Do you think that number is big?

How about the googolplex, which is a one followed by a googol of zeros. The googolplex is so large it doesn't have any meaningful use yet—it is larger than the number of atoms in the universe.

Million and Billion: Some Differences

In the United States—as well as around the world in science and finance—a billion is 1,000 million, which is written as a one followed by nine zeros. This is also called the "short scale."

There is also a "long scale," which is used in France and was previously used in the United Kingdom, in which a billion means one million million. According to this definition of a billion, the number is written with a one followed by 12 zeros. The short scale and long scale were described by French mathematician Genevieve Guitel in 1975.

1. Smith, Roger. "Google Means Every." Research-Technology Management, vol. 53 no. 1, 2010, pp. 67-69, doi:10.1080/08956308.2010.11657613