Group:
Your Name:
Discussion Leader Name:
Recitation Weekly Worksheet #2: Significant Figures
I. Recalling principles
Discussion Leader: What are significant figures? What does it mean for a digit to be significant?
Those nanber that
An inportant part
of
are
meaiyful
the whole number
Discussion Leader: What are the rules concerning whether a 0 is significant?
sering
If there is a decimal point, then the zero before the last important number is not important. If there
is no decimal point, only the zero in the middle of the number is important.
1. Underline the significant digits in each value.
1.0465
亠
0.00289
⼀
0.6730
⼀
1000.00
⼀
220
⼀
Discussion Leader: What is the rule concerning significant figures for addition and subtraction?
If there is a decimal point, then the valid number of the result is equal to
the valid number of the few numbers involved in the addition and
subtraction.
2. What is the result expressed with the correct number of significant figures? 0.03 + 2.179 =?
2 21
.
Discussion Leader: What is the rule concerning significant figures for multiplication and division?
Among the numbers involved in multiplication and division, the number with the
least significant number is equal to the significant number of the result.
3. What is the result expressed with the correct number of significant figures? 8.49 × 3.2 = ?
27
II. Breaking it down
For more complex problems, combine the rules working in steps. For this question, answer each step.
4. What is the result of the calculation below expressed with the correct number of significant figures?
13.18 + 2.8
=
0.6219
Step 1:
•
•
•
•
Remember the order of operations: parentheses, exponents, multiplication and division,
addition and subtraction (PEMDAS, Please Excuse My Dear Aunt Sally).
Treat the numerator and denominator as if they are each separately in parentheses. That is, that
it looks like this:
(13.18 + 2.8)
(0.6219)
So, what do we calculate first? The numerator.
Do not round your answer yet. In general, keep four decimal places for intermediate steps.
13.18 + 2.8 =
13
Step 2:
•
How many sig. figs. does the answer have? Underline the last sig. fig. in the answer from step 1.
It will help you keep track.
Step 3:
•
Do the division.
result of step 1
=
0.6219
=
1 61
.
Step 4:
•
How many sig. figs. does the answer have? Round the final answer to the correct number of
significant figures.
III. Practice problems
Use the same steps to answer the remaining questions. SHOW YOUR WORK! (You do not need to
label step 1, step 2, etc.)
5. What is the result of the calculation below expressed with the correct number of significant figures?
4 19
38.6
=
4.19 − 0.6
逊
.
-
0 6
.
—
.
93
535
“
”
6. Perform the calculation below and report your answer using the correct number of significant
figures.
(47 + 0.8)(0.0869 × 1.023) =
算
8
=
( 0
4L
.
.
0888987 )
11