Transcript sig figures

Significant
Figures
Why do we need significant figures?
Significant figures help us determine
how precisely we measured a given
quantity.The rules governing
significant figures provide a method
to avoid the illusion of a
mathematical operation causing our
answers to become more precise.
There is a trick to determining the
number of significant figures.
Pacific
If there is a decimal
point present, start
counting from the left
from the first nonzero number to the
end
Ex: 0.00670 (3)
Atlantic
If the decimal point is
absent, start counting
from the right from the
first nonzero number
to the end
Ex: 100,200 (4)
143
Three significant digits
All non-zero digits are
significant.
2001
Four significant digits.
All zeros between
significant digits are
significant
17100
Three significant figures
If there is no decimal point
present, zeros to the right of the
last significant digit are not
significant.
1700.
Four significant figures
If there is a decimal point
present, zeros to the right of the
last significant digit are
significant.
12300.0
Six significant figures
If there is a decimal point
present, zeros to the right of the
last significant digit are
significant.
0.0045
Two significant figures
If there is a decimal point
present, zeros to the left of the
first non-zero digit are not
significant.
0.004500
Four significant figures
Zeros to the left of the first
non-zero digit are never
significant.
SPECIAL CASES:
17100
Four significant figures
If there is a bar over a zero,
that is the last significant digit.
SPECIAL CASES
1.4500 x 1045
Five significant figures
If there is scientific notation,
ignore the scientific notation
portion of the number and
solve normally.
Solve the following for significant
figures.
2. 740.
3
1. 57306
5
3. 87,004.2056
9
4. 0.0024
2
5. 726.01
5
6. 450,000
4
7. 0.04040
4
9. 1.0045
5
11. 1,000,000
1
8. 4.012 x 1018
4
10. 6.02 x 1023
3
12. 150.010
6
ADDING AND MULTIPLYING
What is 3.097 + 45.8?
 45.8
 +3.097
 48.897
 Since 45.8 is the least precise number out of
the two, we round our answer to the nearest
tenths place.

48.9
To Add or Subtract
 Line numbers by place value
 Add or subtract
 Round to the LEAST PRECISE place value
 Try:
 320,000 + 346
 35.92 – 8.4
=320,000
=27.5
What is 72 x 405.3?
(2)
72
(4)
 x 405.3
 29681.6
 Since 72 has 2 significant figures
 And 405.3 has 4 significant figures
 The answer can only have 2 significant figures


30000
To Multiply or Divide
 Write the number of significant figures next
to each number
 Multiply or divide
 The answer can only have the LEAST
NUMBER of significant figures
 Try this:
 3.22 x 2.1 =6.8
 36.5 / 3.414 =10.7
Homework Answers
 1) 2
 2) 4
 3) 3
 4) 6
 5) 4
 6) 3
Part B
 1) 25.86 mm
 2) 185.8 Kg
 3) 29.18 s
 4) 15.1 mL
 5) 20. cm3
 6) 2900 m3
 7) 5.53 mm2

 Part A
7) 5
8) 3
9) 5
10) 6
11) 3
12) 3