The Metric System
Length
• The metric system is an international system of measurement.
• All sciences use the metric system.
• The United States is the only industrialized nation in the world
that does not use the metric system as their official
measurement.
• Even though it is not our official system of measurement, we still
use the metric system in various aspects of our lives.
Metric System
• The three prefixes that we will use
the most are:
– kilo
– centi
– milli
Base Units
kilo
hecto
deca
meter
gram
liter
deci
centi
milli
Metric System
• These prefixes are based on powers of 10.
What does this mean?
– From each prefix every “step” is either:
• 10 times larger
or
• 10 times smaller
– For example
• Centimeters are 10 times larger than millimeters
• 1 centimeter = 10 millimeters
Base Units
kilo
hecto
deca
meter
gram
liter
deci
centi
milli
Metric System
– Centimeters are 10 times
larger than millimeters so it
takes more millimeters for the
same length
1 centimeter = 10 millimeters
Example not to scale
40
1 mm
41
1 mm
1 mm
1 mm
1 mm
1 mm
40
1 mm
1 mm
1 mm
1 mm
41
1 cm
Move right : multiply by a power of 10 for each step
kilo
hecto
deca
meter
liter
gram
deci
centi
Move left: divide by a power of 10 for each step.
Convert 4cm to mm
You are moving right 1 step
so you multiply by 10
4 x 10 = 40
4cm = 40mm
Convert 34 mm to cm
You are moving left 1 step
So you divide by 10
34 ÷ 10 = 3.4
34 mm = 3.4 cm
Convert 5m to cm
You are moving right 2 steps
so you multiply by 100
5 x 100 = 500
5 meters – 500 cm
Convert 34 mm to m
You are moving left 3 steps
So you divide by 1000
34 ÷ 1000 -= .034
34 mm - .034 meters
milli
Metric System
• Now let’s start from centimeters and convert
to kilometers
400000 centimeters = 4 kilometers
400000 centimeters = 4.00000 kilometers
kilo
hecto
deca
meter
liter
gram
deci
centi
milli
Metric System
• Now let’s start from meters and convert to centimeters
5 meters = 500 centimeters
kilo
hecto
deca
meter
liter
gram
deci
centi
milli
• Now let’s start from kilometers and convert to meters
.3 kilometers = 300 meters
kilo
hecto
deca
meter
liter
gram
deci
centi
milli
Move right : multiply by a power of 10 for each step
kilo
hecto
deca
meter
liter
gram
deci
Move left: divide by a power of 10 for each step.
You Try:
8 m = _____cm
120 cm = _____m
44 mm = _____mm
92 cm = _____mm
150 m =______km
7 km = ______m
centi
milli
Metric System
• Summary
– Base units in the metric system are meter, liter,
gram
– Metric system is based on powers of 10
– For conversions within the metric system, each
“step” is 1 decimal place to the right or left
– Using the diagram below, converting to the right,
moves the decimal to the right and vice versa
kilo
hecto
deca
meter
liter
gram
deci
centi
milli
Reading a Metric Ruler
All metric rulers are numbered with centimeters (although they may
show mm, cm, or metric)
The longer lines on the metric
ruler are called…
• centimeters
The shorter lines on the metric
ruler are called…
• millimeters
A
B
To read in centimeters write down how many whole centimeters and then
each line after is .1 of a centimeter.
Arrow A above is one line past 12 centimeters therefore it is 12. 1 cm.
Arrow B is four lines past 15 centimeters therefore it is 15.4 cm
A
B
If you needed to measure in millimeters it is easier to measure in
centimeters first and then convert to millimeters by multiplying by 10.
Arrow A is 10.7 cm = 107 mm
Arrow B is 14.1 cm = 141 mm
______cm
______cm
______cm
______mm
______mm
______mm