Significant Figures

Significant Figures

All measurements are inaccurate

Precision of measuring device

Human error

Faulty technique

Significant Figures

Measurements need to convey precision

Must include degree of uncertainty

Sig Figs tell us

Significant Figures

Significant Figures
1.
Significant figures in a measurement include
 all of the digits that are known precisely
 plus one last digit that is estimated .

Significant Figures
2. Non-zero digits are always significant.
1 0 3 .
23 000 2

Significant Figures
3. All final zeros after the decimal point are significant.
12.74
0
0.042
0

Significant Figures
4. Zeros between two other significant digits are always significant.
1 0 .0
2 00 4
6.
00 0

Significant Figures
5. Zeros used only for spacing the decimal point are
.
1 00
0.00000
233


Always put a 0 in front of a decimal point

0.247


0.0042


.873


1) 400
3) 0.0001
5) 320
7) 22 568
Significant Figures
2) 200.0
4) 218
6) 0.00530
8) 4755.50

1) 4.0 x 10 3
Significant Figures
2) 1.67 x 10 -8
3) 5 x 10 12 4) 2.00 x 10 4
5) 635.000
7) 5201
6) 22 000
8) 81

Significant Figures
6. If you add or subtract, the answer is rounded to the same number of decimal places as the measurement with the least number of decimal places.

Significant Figures
7. If you multiply or divide two numbers, the answer is rounded off to the number of significant figures in the least precise term used in the calculation (i.e. the number with the fewest sig figs).

Calculations

Calculations