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CH 36  METRIC SYSTEM:
THE GRAM
 Introduction
A while back we visited the metric system for the first time in this book
when we studied the metric unit of length, the meter. There we learned
what a meter was, why it’s actually easier to work with meters than
with feet and yards, and how the other units of length in the metric
system (mm, cm, km) were obtained from the basic unit meter by
attaching prefixes (milli, centi, kilo) to the front of the word meter.
We now revisit the metric system, this time studying the units of
weight. To be precise, we’re going to study the units of mass. Ask your
science teacher to explain the difference between mass and weight.
 The Gram
The unit of weight (actually mass) in the metric system is the
gram, and is abbreviated by the letter “g”. So the measurement
“25 g” means 25 grams. One way to help get a feel for the weight of one
gram is to remember that one raisin weighs about one gram. Also, if
you had 1,000 grams of sirloin steak, you would have approximately
2.2 lb of beef.
A gram is a pretty small weight; it’s about 1 of an ounce. And still
28
another way to think of a gram is that there are about 454 grams to the
pound. If you take the meat from a Quarter Pounder (4 ounces) and
divide it up into about 100 parts, each part would be about a gram.
That’s small (especially if you’re hungry), but from some perspectives a
Ch 36  Metric System: The Gram
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gram is considered a lot. For example, the
federal penalty for selling just five grams of crack
cocaine is a mandatory five-year prison term.
As small as a gram is, a single gram of many
medicines could easily kill you instead of cure you, and that’s why
medicine may use smaller units of weight like milligrams, micrograms,
or nanograms. Moreover, trying to describe the weight of the Earth in
grams would require a humongous number, so we also need a larger
unit of weight. The good news: There are no new prefixes to learn here
(although there are many others that you’ll learn in future math,
computer, and science classes).
By the way, we have just listed a whole bunch of ways that grams
relate to various items and U.S. measurements. Ask your teacher
which ones you’ll have to memorize.
Prefix
Abbreviation Meaning
kilo
k
centi
c
milli
m
1,000
1/100 or
0.01
1/1,000
or 0.001
Example
1 kg = 1,000 grams
1 cg = 1/100 of a gram
1 mg = 1/1,000 of a gram
Here are some examples:
1.
7 kg = 7,000 g
Since 1 kg = 1,000 g, it follows that 7 kg = 7,000 g.
2.
1 kg = 500 g
2
Again, if 1 kg = 1,000 g, then half of a kg is half of 1,000.
3.
500 cg = 5 g
100 cg = 1 g, so 500 cg = 5 g.
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4.
50 cg = 1 g
2
Since 100 cg = 1 g, and 50 is half of 100, it follows that
50 cg = 1 g.
2
5.
8,000 mg = 8 g
It takes 1,000 mg to make 1 g, so 8,000 mg would make 8 g.
6.
750 mg = 3 g
4
Well, since 750 is 3 of 1,000, then 750 mg = 3 g.
4
4
Homework
1.
A gram is what fraction of an ounce?
2.
A kilogram weighs about _____ pounds.
3.
a. 1 kg = _____ g
b. 1 cg = _____ g
c. 1 mg = _____ g
d. 1 g = _____ kg
e. 1 g = ____ cg
f. 1 g = _____ mg
4.
How many kg are there in
a. 1000 g
5.
c. 250 g
d. 500 g
e. 750 g
c. 14 g
d. 1 g
e. 3 g
c. 3 g
4
d. 1 g
2
e. 1 g
4
How many cg are there in
a. 1 g
6.
b. 9000 g
b. 3 g
2
4
How many mg are there in
a. 1 g
b. 7 g
Ch 36  Metric System: The Gram
200
Find a reasonable unit in the Metric system to measure:
7.
the weight of an ant
8.
the weight of a turkey
9.
the weight of a Toyota
10.
the weight of a cup of cereal
Choose the measurement which represents the greatest weight:
11.
1g
1 mg
1 cg
1 kg
1 lb
12.
1 ton
1 kg
1 lb
1 mg
1g
13.
14 oz
2,000 mg
0.5 kg
400 g
1.3 lb
14.
1,900 lb
1 ton
1,000 kg
5,000 oz
5,000 g
15.
700 g
1 kg
1,500 mg
80 cg
2.1 lb
Solutions
1.
1/28
3.
a. 1000
d. 0.001 or 1/1000
b. 0.01 or 1/100
e. 100
4.
a. 1
b. 9
c. 0.25 or 1
d. 0.5 or 1
e. 0.75 or 3
5.
a. 100
b. 300
c. 1400
d. 50
e. 75
6.
a. 1000
b. 7000
c. 750
d. 500
e. 250
7.
mg (or possibly cg)
11. 1 kg
2.2
2.
12. 1 ton
4
8.
c. 0.001 or 1/1000
f. 1000
2
kg (or possibly g)
13. 1.3 lb
9.
14. 1000 kg
4
kg
10. g
15. 1 kg
“A man who has never gone to school may steal from a freight car; but
if he has a university education, he may steal the whole railroad.”
Theodore Roosevelt
Ch 36  Metric System: The Gram