a decagram or star shape composed of ten points

Math uses prefixes to provide clues about measurements. The Metric System, for example, uses prefixes to assign a quantity to a "base unit" or "root word." One example is shown below.



in words



Expressed in a sentence




I’m running in the Jingle Bell 5K. That’s five kilometers or 3.1 miles!

Study some examples using "meter," which can be used to measure distance, as the root word. If friends told you that they were running a kilometer, how many meters would that be? You can find the answer in the chart that follows.


Number of meters















The answer is 1,000 meters. Now let’s see if you can use the same knowledge and apply it to a different unit of measurement. This time you are looking at capacity, which is measured in "liters" in the Metric System.


Number of liters















Use the chart above to answer this question: If someone told you that they needed a kiloliter of gasoline, how many liters would that be?

If you thought it would be 1,000 liters, you are correct. Do you understand how a kilometer and a kiloliter are 1,000 times the basic unit of measure?

Read the following article from the New York Times and focus on what you have learned about math prefixes. The article discusses a term that was used to refer to the new millennium (the 2000s). Prior to 2000, some people feared that there would be widespread chaos and destruction as we entered a new 1,000-year period. If the people in the article had known the prefix for “1,000,” it would have helped them tremendously.

‘Y2K’ Stands for the Year 2000. Now That Wasn’t Really Difficult, Was It?


“Ka-blam!” Edyth Florio, a third grader at Public School 234 in Greenwich Village, responded assuredly. “Because the whole world is going to go bonkers.”

“The 2 is 2000, the K is for knockout, and Y? I have no idea,” said 28-year-old Anthony Reiss, hanging out with a friend selling Christmas trees on Seventh Avenue.

“K is obviously a Roman numeral,” said 45-year-old Joe Grahek. “It’s a quick way of saying 2000. Y, I’m not sure.” But then Mr. Grahek, who works for a government agency he did not want to specify, ventured a guess. Borrowing from algebra, he ventured: “It’s a missing piece. In other words, you have X and you try to determine Y.”

So went the answers to the question: What, exactly, does Y2K stand for? And fair enough, many of those informally polled responded with the impossibly simple yet correct: Year 2000. But . . . a surprising number of people were in league with Edyth, Anthony and Joe.

“Let’s clear up the specifics straight away. The abbreviation is a combination of Greek and geek, with Y standing for year, and 2K short for 2000. The K comes from the Greek prefix, kilo-, which was brought into more common usage in 1795, when the French instituted the metric system, according to Elizabeth Jewell, managing editor and acting director of United States dictionaries for Oxford University Press. The abbreviation became popular in computer circles, as programmers began trying to solve the glitches expected on Jan. 1.

At least little Edyth was on the right track, sort of. She actually got the Y and 2 right; but that darn K. But she was a lot closer than a classmate, Noemi Bilger, who chimed in with a “Katalog?”

Sabrina Wolf, another third grader, guessed that the K stood for the Kind of year coming up.

At a Midtown office of the Department of Motor Vehicles, on 34th Street, Thomas Jacobsen, 19, a retail worker from the Bronx, said he had never really thought about what the characters meant.

Nearby, Connie Marhefka, an administrative assistant in charge of millennial preparations for her office, had heard others suggest that the K was for Katastrophe.

John Monahan, 45, who works with rigging for theatrical delivery, treated it more as an existential question. “It doesn’t matter; we’ll all be dead by the 1st,” he said, standing at the back of a truck outside the Helen Hayes Theater. “Y2? ‘Cause one time ain’t enough.”

If the people in the article had had a little knowledge of affixes, they would have been able to guess that “K” equaled “kilo,” which equals 1,000. The “Y” might still have been a mystery, but they would have been closer to solving the meaning of “Y2K.”

take notes icon Now it’s your turn to show what you have learned. Can you use affixes in math class to solve a word problem? Try it out and see. Use your notes to write your answer. When you’re finished, check your understanding.

Problem: Jesse wants to train for a decathlon but doesn’t know where to start. He asks his track coach to help him out and the coach creates a training program that targets only half the events. The track coach suggests that Jesse ask the athletic director to create the rest of the event’s workouts.

How many event workouts did the track coach create?

  1. 2
  2. 3.33
  3. 5
  4. 7.5
Check Your Understanding

c. 5

Let’s look more closely at the correct answer.

Deca- means “10.” So if the track coach came up with half of the student’s training program, he created training for five events. (Five is half of 10.)


Affixes not only help you understand the language of math, but they also can help you solve math problems!