Transcript Significant Figures -why we use them -rules for sig. figs. -operations with sig. figs.

Significant
Figures
-why we use them
-rules for sig. figs.
-operations with sig. figs
What are Significant Figures?
• They are all the numbers in a
measurement that are known with
certainty plus the first digit that is
uncertain.
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
SIDENOTE:
•You will hear significant figures
also called:
•Significant digits
•Sig figs
Significant Figure Rules
1) All non-zero digits and zeros
between non-zero digits are
significant.
22.75
4007
2) Leading zeros are not
significant.
0.75
0.0000337
3) 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
4) For values written in scientific
notation, the digits in the coefficient
are significant.
23
6.02x10
-6
3.00x10
How many
SIGNIFICANT FIGURES
are in the following
numbers?
83.591
5007
10.005
20 080
1 000 000
0.0012
1.007
196.0
75000.
1.52x10
22
-6
2.00x10
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?
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?
Do the following
problems with the
correct number of
SIGNIFICANT FIGURES.
24 x 31.8
8.4/4.2
49.1 – 8.001
81.350 + 7.35
0.0056 x 3.227
1007/33.6
20300 – 2878.6
1.005 – 3.60
76.00 x 13
21
1.5x10
x
13
2.07x10
6
19
1.8x10 /2.77x10