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### Course: 4th grade>Unit 14

Lesson 7: Converting units of length

# Metric units of length review (mm, cm, m, & km)

Review the size of millimeters, centimeters, meters, and kilometers and how to convert between them.  Then, try some practice problems.

## Summary of metric units of distance

KilometerMeterCentimeterMillimeter
$1$$1000$$100,000$$1,000,000$
$\frac{1}{1000}$$1$$100$$1000$
$\frac{1}{100,000}$$\frac{1}{100}$$1$$10$

## What is distance?

Distance measures length. For example, the distance of a road is how long the road is.
In the metric system of measurement, the most common units of distance are millimeters, centimeters, meters, and kilometers.

### How big are metric units of distance?

A paper clip is about $1$ millimeter thick.
A fingernail is about $1$ centimeter wide.
The length of a guitar is about $1$ meter.
A kilometer is equal to $1000$ meters. It is a little over half of a mile.
Want to learn more about metric units of distance? Check out this video.

## Practice set 1: Estimating distance

Problem 1A
Identify the most reasonable unit to measure the distance from New York to California.

Want to try more problems like this? Check out this exercise.

## Converting larger units to smaller units

To convert larger units to smaller units we multiply the number of larger units by the green conversion factor for the appropriate smaller units.
Example: Converting meters to centimeters:

## Converting smaller units to larger units

To convert smaller units to larger units we divide the number of smaller units by the purple conversion factor for the appropriate larger units.
Example: Converting meters to kilometers:
Want to learn more about converting between metric units of distance? Check out this video.

## Practice set 2: Converting distance units

Practice 2A
Convert.
$5$ meters $=$
millimeters

Want to try more problems like this? Check out these exercises:
Convert larger units to smaller units
Converting between units

## Want to join the conversation?

• What about micrometers?
• #1, I love the name, #2, A micrometer is 1000 times smaller than a centimeter.
• Is there anything before 'Millimeter' and after 'Kilometer' ?
• technically, as with any SI unit, yes there is.
practically: smaller than milli meter: yes. larger than kilo meter: no
this table shows all the possible prefixes: https://en.wikipedia.org/wiki/Metric_prefix

in physics, you occasionally come across nano meters, one nanometer = 10^-9 meters or 0.000000001 meters

going bigger, you could technically have a mega meter which would be 1000 kilometers, but i have never seen this in practice and most people would misunderstand you (in a metric country)
• What is the difference between km and M?
• a km is a kilometer, and an M is a meter. There are 1,000 meters in a kilometer. In other words, one meter is 1/1,000 of a kilometer or 0.001 of a kilometer.
• I get messed up with km to mm.
• Converting from km to m requires multiplying by 1,000, because there are 1,000 m in one km.

Converting m to mm requires multiplying by 1,000, because there are 1,000 mm in one m.

It follows from these two facts that converting from km to mm requires multiplying by 1,000*1,000=1,000,000.

Have a blessed, wonderful day!
• How many millimeters are in 5 meters?
• 5000 millimeters
• Is there more measurements than just this?
• Yes- nanometers and micrometers are some smaller measurements
• I have one tree that is 4 meters tall a second tree that is 3 m tall how many centimeters taller is the first tree
• 100 cm is the answer
• Okay so if y'all don't get this, let me give you an example. So, 1 kilogram = 1,000 grams, right? So, if the question asks you how many grams are 4 kilograms, you multiply 4 by 1,000 which is 4,000. Because if 1 kilogram = 1,000 grams, 4 must be 4,000 grams.
• thx for that