The following numbers have 1
significant figure:
3
40
0.1
0.0002
5 x 106
The following numbers have 2 significant
figures:
0.00016 1.0 37 450 2.5 x 10-2
The following numbers have 3 significant
figures:
42.9
0.000116
870.
725
5.10
The following numbers have 4 significant
figures:
870.0
0.0001100
3125
2500.
Write some “rules” for how to
determine which digits are
significant and which digits
aren’t significant.
- Any non-zero digit is significant.
- Zeroes to the left of a decimal that is shown
are significant. (e. g. 2500.0 All these zeroes
are significant)
- Leading zeroes are not significant, i. e., any
zero to the left of a non-zero digit is not
significant. (e. g. 0.00001 all these zeroes are
to the left of the first non-zero digit, so they
are not significant)
Rules continued…
Zeroes to the left of an “invisible” decimal are not
Significant--they are called “trailing zeroes”. (e. g. 870
There is no decimal shown, so the zero is not significant.)
-Zeroes to the right of a shown decimal are significant if they
also occur to the right of a non-zero digit. (e. g. 70.0 The
Right-most zero is significant because it occurs to the right
Of a non-zero digit and the decimal is shown
Rules Continued…
- When adding or subtracting 2 numbers,
the number with the least number of
decimal places determines the amount
of decimal places in the answer.
- E. g. 3.01 - 2.0 = 1.0 The fewest
number of decimal places was “1”, so
there is only 1 decimal place in the
answer
Rules, Continued
• When multiplying and dividing, the
number with the fewest significant
figures determines how many significant
figures are in the answer.
• E. g. 0.25 x 4000. = 1.0 x 103
Create 2 numbers that have:
•
•
•
•
1 sig fig: _4___, _0.01___
2 sig figs: _0.021___, _0.35__, 250__
3 sig figs: _267___, __300.__
10 sig figs: __0.1 000 000 000___,
_70.00000001_____
How many signficant figures
do the following numbers
have?
1.23400
1.20 x 10-2
1,234,000
5000
0.00012
0.000009