Significant Figures

1
Significant Figures

• -why we use them
• -rules for sig. figs.
• -operations with sig. figs

2
What are Significant Figures?

• They are all the numbers in a measurement that
  are known with certainty plus the first digit
  that is uncertain.

3
Why use Significant Figures?

• Significant figures are needed in science,
  because the tools we use to measure are not
  infinitely precise.
• How accurate is a
• Meterstick
• Electronic balance
• Graduated cylinder

4
SIDENOTE

• You will hear significant figures also called
• Significant digits
• Sig figs

5
Significant Figure Rules

• 1) All non-zero digits and zeros between
  non-zero digits are significant.

22.75 4007
6

• 2) Leading zeros are not significant.

0.75 0.0000337
7

• Zeros to the right of all non zero digits are
  only significant if the decimal point is shown
  (or if a bar is placed over the zero).

780 27.00 0.0300
8

• 4) For values written in scientific notation,
  the digits in the coefficient are significant.

6.02x1023 3.00x10-6
9
How many SIGNIFICANT FIGURES are in the following
numbers?
10
83.591
11
5007
12
10.005
13
20 080
14
1 000 000
15
0.0012
16
1.007
17
196.0
18
75000.
19
1.52x10 22
20
2.00x10-6
21
Multiplying/Dividing with Sig Figs

• When multiplying or dividing using significant
  figures, the product or quotient will contain the
  same number of significant figures as the number
  with the least significant figures.

What is 23.95 x 11.7?
22
Adding/Subtracting with Sig Figs

• When adding or subtracting with significant
  figures, the sum or difference has the same
  number of decimal places as the measurement with
  the least number of decimal places.

What is 23.95 11.7?
23
Do the following problems with the correct number
of SIGNIFICANT FIGURES.
24
24 x 31.8
25
8.4/4.2
26
49.1 8.001
27
81.350 7.35
28
0.0056 x 3.227
29
1007/33.6
30
20300 2878.6
31
1.005 3.60
32
76.00 x 13
33
1.5x1021 x 2.07x1013
34
1.8x106/2.77x1019