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Significant Figures
How to count the number of significant figures in
a decimal number.
Zeros Between other non-zero
digits are significant.
a. 50.3 has three significant
figures
b. 3.0025 has five significant
figures
Significant Figures
Zeros in front of nonzero digits are not
significant:
0.892 has three significant figures
0.0008 has one significant figure
Significant Figures
Zeros that are at the end of a decimal
number are significant.
57.00 has four significant figures
2.000000 has seven significant figures
At the end of a non-decimal number they are not.
5700 has two significant figures
2020 has three significant figures
Non-Decimal Numbers
Major pain to try to figure out the
significant figures – it depends on the
number’s history.
Don’t Use Them.
Practice
Find the number of significant figures.
1.
2.00450
2. .0034050
3.
4.
1450
0.02040
1.
6 sf’s.
2.
5 sf’s
3.
3 sf’s
4.
4 sf’s
Significant Figures
After Division and Multiplication
After performing the calculation,
note the factor that has the least
number of sig figs. Round the product
or quotient to this number of digits.
3.22 X 2.1 = 6.762  6.8
36.5/3.414 = 10.691  10.7
Significant Figures
• Addition or subtraction with significant
figures:
– The final answer should have the same
number of digits to the right of the
decimal as the measurement with the
smallest number of digits to the right of
the decimal.
Ex:
97.3 + 5.85 = 103.15  103.2