The metric system is the most widely used measurement system in the world, and it uses prefixes to show different values. Let’s learn about the metric system as well as prefixes and what they mean.

## What Is the Metric System?

The **metric system** is a system of measurements that’s used in everyday activities and science. Most countries in the world use it as their primary measurement system, except the United States and a few smaller counties. It’s also the universal form of measurement for the scientific community–the metric system allows scientists a standard for communicating numbers, making experiments easier to understand and replicate.Much like the place value chart you learned about in math class, the metric system is a **base-10** system, which means it is based on the number 10.

When you move one place to the left, the next value is 10 times larger. When you move one place to the right, the value is 10 times lower. Think of it like a staircase:

## Metric Prefixes

The metric system uses three standard units:

- Liters are used to measure liquid volume (how much space liquid takes up).
- Grams are used to measure mass (how much of an object there is).
- Meters are used to measure distance (the amount of space from one point to another).

These three standard units are the starting points for the metric system, similar to the ones spot on a place value chart. In order to make these standard units bigger or smaller, we use prefixes. A **prefix** is a word attached to the front of another word to change its meaning.

Now, let’s explore the basic metric prefixes:

#### Prefixes That Mean Smaller

Let’s start at the basic unit and move downward to the smaller units:

*Deci*: A unit with the prefix*deci-*means that it is one-tenth the amount of the original unit. So, a decigram is one-tenth of gram. You could turn the 1.0 decigram into a gram by moving the decimal point once to the left (0.1).*Centi*: A*centi-*unit is one-hundredth the original unit.So, saying that you have 1.2 centiliters would be the same as saying you have 0.012 liters (the decimal point is moved two to the left).

*Milli-*: When you want to measure the length of something very, very tiny, you use a millimeter. The prefix*milli-*means one-thousandth.So, a milliliter is one-thousandth of a liter.

As you can see, to move down one step at any point on the metric staircase, you simply divide by 10 (or move the decimal one to the left). That’s why it’s called a base-10 system!

#### Prefixes That Mean Larger

Now, let’s start at the basic unit and climb the staircase up to the larger units:

*Deca-*: A*deca-*prefix attached to a unit of measurement means that the value is 10 times the original unit. It’s similar to the tens place on a value chart.*Hecto-*:*Hecto-*is simmilar to the hundreds place on the place value chart–a*hecto-*unit is 100 times larger than the original unit.So, a hectogram is 100 grams.

*Kilo-*: The*kilo-*would be the thousands place on the place value chart–a*kilo-*is 1,000 times larger than the basic unit. So, a kilometer is 1,000 meters.

As you can see, to move up one step at any point on the metric staircase, you simply multiply by 10. That’s why it’s called a base-10 system!

## Lesson Summary

The metric system is similar to decimal notation in that both are base-10 systems.

It uses prefixes (words attached to the front of the basic units) to show different values. When moving along the metric staircase, you move up one step by multiplying by 10, and you move down one step by dividing by 10.