Addition
or Subtraction using Significant Figures:
The answer can have no more figures to
the right of the decimal point than there are in the measurement with
the smallest number of figures to the right of the decimal point.
Example:...2.87
......(2 sig. figs to the right of the decimal)
........ ..........3.5673 ..(4
sig. figs to the right of the decimal)
...........+ 301.2 .........(1
sig. fig. to the right of the decimal)
..............307.6373> rounds off to
307.6 (our answer can only have
one figure after the decimal)
2.
Multiplication or Division using Significant Figures:
The answer can have no more significant
figures that there are in the measurement with the smallest number of
significant figures.
Example:
12.257.... (5 total significant figures)
.................x 1.162 ....(4
total significant figures)
................14.2426 > rounds off
to 14.24 (4 total significant figures)
HINT:
Students
often have difficulty remembering the rules for using significant figures
in calculations and that makes them very sad…putting them in A
SAD MODE.
A:
addition 
M:
multiply 
S:
subtraction 
O:
or 
A:
after 
D:
divide 
D:
decimal 
E:
everything 
If
you Add or
Subtract, look After
the Decimal
for significant figures. 
If
you Multiply
Or Divide look
at Everything (the entire
number) for significant figures. 
As
a rule, when performing a series of calculations, wait until the very
end to round off to the proper number of significant figures instead of
rounding off each intermediate result.
