Transcript Significant Figures Notes

Significant Figures
Rule 1:
• Nonzero numbers are always significant.
• Ex.) 72.3 has 3 sig figs.
Rule 2:
• All final zeroes to the right of the decimal
are significant.
• Ex.) 72.30 has 4 sig figs.
Rule 3:
• Any zero between significant figures is
significant.
• Ex.) 702.3 has 4 sig figs.
Rule 4:
• Placeholder zeroes are not significant. To
remove place holder zeroes, rewrite the
number in scientific notation.
• Ex.) 0.0034984 has 5 sig figs.
• Ex.) 4390 has 3 sig figs.
How many sig figs here?
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1.2
2100
56.76
4.00
0.0792
7,083,000,000
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•
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2
2
4
3
3
4
How many sig figs here?
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•
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3401
2100
2100.0
5.00
0.00412
8,000,050,000
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4
2
5
3
3
6
What about calculations with
sig figs?
• Rule: When adding or
subtracting numbers, your
answer can have no more
places after the decimal than
the LEAST of the measured
numbers.
Add/Subtract examples
• 2.45cm + 1.2cm = 3.65cm,
• Round off to
= 3.7cm
• 7.432cm + 2cm = 9.432
• Round off to = 9 cm
Multiplication and Division
• Rule: When multiplying
or dividing, the result
can have no more
significant figures than
the least reliable
measurement.
A couple of examples
• 56.78 cm x 2.45cm = 139.111
• Round to
 139cm2
• 75.8cm x 9.6cm = ?
2
cm