• measured certain digits.• last digit is estimated, but IS significant.

• do not overstate the precision

5.23 cm

5.230 cm

Significant Figures (Sig Figs)

(uncertain)

1. All nonzero digits are significant.

2. Captive Zeroes between two significant figures are significant.

3. Leading Zeroes at the beginning of a number are never significant.

4. Trailing Zeroes are significant at the end of a number IF there is a decimal.

0.0003700400 mSignificant Figures

0’s

round answers to keep the fewest decimal places

round answers to keep the fewest significant figures

Significant Figures

+ or –

x or ÷

3.48 g + 2.2 g =

6.40 cm x 2.0 cm =

5.68 5.7

12.8 13

1. How many sig figs are in each number?(i) 250.0 mL(ii) 4.7 x 10–5 kg(iii) 34000000 mg(iv) 0.03400 m

2. Round the answer to the correct sig figs. (i) 34.5 m x 23.46 m (ii) 123 g ÷ 3 mL (iii) 23.888897 g + 11.2 g (iv) 3.00g – 2.0 g ÷ 4 cm3

4

224

809 m2

40 g/mL

35.1 g0.3 g/cm3

Quick Quiz!

1.0 g