Discovery Activity Significant Figures Chapter 2
The following is a list of numbers. The number of significant figures in each number
is written in the parenthesis after the number.
Find the pattern, and write a rule
telling what digits are not significant.
125(3)
0.0122 (3)
133.8(4)
0.00120 (3)
1002 (4)
0.0001225 (4)
1.9 X 10
2
(2)
10000 (1)
3.20 X 10
4
(3)
1000.
(4)
0.025200 (5)
5.888 X 10
3
(4)
100.0 (4)
3.002 X 10
3
(4)
100 (1)
1230 (3)
1230. (4)
120.0 (4)
5230.00 (6)
523000 (3)
850 (2)
What digits are not significant?_______________________________________
_______________________________________________________________
All other numbers are significant.
Multiplying and Dividing Using Significant Figures
Observe the following problems and answers.
Write a rule explaining how many
significant figures to put in the answer of a multiplication or division problem.
3.21 X 21 = 67.41 correct answer 67
7.86 X 2.333 = 18.33738 correct answer 18.3
3.1122 X 4.531 = 14.101378 correct answer 14.10
400 X 3.44 = 1376 correct answer 1000
145.6/25 = 5.824 correct answer 5.8
9.85 / 4.152 = 2.37235 correct answer 2.37
145.3/2.88 = 50.451389 correct answer 50.5
Rule:
___________________________________________________________________
1
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View Full DocumentAdding and Subtracting Using Significant Figures
Observe the following problems and answers.
Write a rule explaining how many
significant figures to put in the answer of an addition or subtraction problem.
1.22 + 9 = 10.22correct answer 10
11 + 9.311 = 20.311 correct answer 20
9.1 + 8.201 = 17.301 correct answer 17.3
300  23.45 = 276.55 correct answer 277
98.71  5.222 = 93.488 correct answer 93.49
Rule:
___________________________________________________________________
Explain how the rules for multiplication/division differ from addition /subtraction.
______________________________________________________________________
Scientific Notation
Observe how to change numbers in and out of scientific notation.
1005 = 1.005 X 10
3
( this really means 1.005 X 10 X 10 X 10)
452 = 4.52 X 10
2
0.00123 = 1.23 X 10
3
( this really means 1.23
)
10x10x10
0.0003697 = 3.697 X 10
4
A positive exponent, like 10
2
, means multiply the number by 10X 10, or 100, making
the number larger.
A negative exponent like 10
2
means to divide the number by 10X 10, or 100, making
the number smaller.
Now, go to the website and connect to the link: Homework problems with answers
Chapter 2.
Complete the worksheet by next class period and bring it to class.
When writing numbers in scientific notation, all of the numbers you write are
significant.
1.020 X 10
4
( 4 significant figures ignore the 10
4
part of the number.)
5.8102 X 10
3
(5)
That is why it is good to write numbers in scientific notation. All the numbers are
always significant. (Scroll to next page for answers)
To get the answers for this
worksheet go to the website: http://dipowell1.home.mindspring.com (Link:
Discovery activity significant figures chapter 2 scroll to page 3 for answers)
2
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 Spring '10
 dickpowell
 pH, Decimal

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