SIGNIFICANT FIGURES
Significant Figures
: Many of the numbers in science are the result of MEASUREMENTS and therefore
are subject to some degree of EXPERIMENTAL UNCERTAINTY.
A rough indication of the uncertainty
is implied by the number of digits used.
EXAMPLE: 2.50 m could mean that we expect the answer to be
between
2.495 m and 2.505 m (i.e.
±
0 005
.
m ).
Significant
figures refer to the fact that we have a reliable
digit that we know with certainty.
RULES
:
1)
The number of significant figures when
no decimal
point is indicated is equal to the number of
digits.
EXAMPLE: 123 has 3 significant digits; 1972 has 4 significant digits.
2)
The number of digits to the
left
of the decimal point are SIGNIFICANT if and only if they are
NOT ALL ZEROS.
The number of digits to the
right
of the decimal point is SIGNIFICANT
provided the numbers to the left of the decimal point are NOT ALL ZEROS.
EXAMPLES
1023.0 has 5 significant figures whereas 0.001 has only 1 significant digit.
0.00001020 has 4
significant figures, namely
1020
.
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 Spring '09
 TANNY
 Calculus, Scientific Notation, Decimal

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