1. Significant Measurements
-significant figures are a way to report scientific values
-significant figures are useful for expressing certainty
ie. A length of 6.36 cm – last digit “6” is a guess or
estimate
Rules for Significant Figures
-zeroes appearing between nonzero digits are significant
ex L = 3 sig figs
km = 5 sig figs

2. Significant Measurements
-zeroes appearing in front of non zero digits are not significant
ex m = 5 sig figs
kg = 1 sig fig
-zeroes at the end of a number and to the right of the decimal are significant
ex = 4 sig figs
= 10 sig figs
-zeroes at the end of a number, but BEFORE/LEFT OF the decimal may or may not be significant. It depends if you SEE the decimal.
ex m = 1 sig fig
2000. m = 4 sig figs

3. Significant Measurements
Adding or Subracting Significant Figures
-When adding or subtracting, the answer must have the same number of digits to the right of the decimal point as the measurement with the fewest digits to the right of the decimal point.
ex g g g =
w/ significant figures = 27.1
Multiplying or Dividing Significant Figures
-When multiplying or dividing, the answer should have no more significant figures than the measurement with the fewest number of significant figures
ex g ÷ mL = g/mL
w/ significant figures = g/mL

4. Significant Measurements
Scientific Notation
-scientific notation can be used to shorten very large or very small numbers
-scientific notation can be used in conjunction with significant figures
-many scientific notations use two or three significant figures
ex. 3,957,309,204 becomes × 109
becomes 7.48 × 10-11
-the exponent by the “10” is determined by how many decimal places must be moved

5. Significant Figures Practice
Write down the numbers and how many significant figures each one has as well as what kind of quantity is being measured (ie. mass, pressure, length, temperature, volume, etc): g L
3. 910°C atm kg