Significant Figures

1. Significant Figures SIG FIGS!!!!!!!

2. Importance of Sig figs • Sig figs tell people the precision of a value. • Precision: how many times you can achieve the same result. (dart and #19 over and over) • Accuracy: how close your value is to the true value (dart and bulls-eye)

3. Rule #1 • All real numbers are sig figs. • Ex. 1235 (4) • Ex. 4487558 (7) • Ex. .2257 (4) • Ex. 14.88597 (7)

4. Rule #2 • All zeros between real numbers are sig figs. • Ex. 2007 (4) • Ex. 24.0559 (6) • Ex. 800000000000000004.05 (20)

5. Rule #3 • All zeros behind a real number in FRONT of a decimal are not sig figs. • Ex. 5000 (1) • Ex. 410 (2) • Ex. 100000 (1)

6. Rule #4 • All zeros BEHIND the decimal and in FRONT of a real number are not sig figs. • Ex. 0.0045 (2) • Ex. 0.0000078 (2)

7. Rule #5 • All zeros BEHIND the decimal and BEHIND a real number are sig figs. • Ex. 0.22570 (5) • Ex. 0.998700 (6) • Ex. 45.10 (4) • Ex. 0.004580 (tricky…the underlined zeros do not follow this rule.. 4)

8. How many sig figs? #1 50069 (?) • 5sf #2 50069.004 (?) • 8sf #3 448.000 (?) • 6sf #4 8000 (1) • 1sf

9. Addition and subtraction • When adding and subtracting—pay attention to the number of digits behind the decimal point. • Lowest number wins! • Ex. 12.005 3 digits behind + 1.01 2 digits behind 13.015 = 13.02 2 digits behind

10. Multiplication and division • When multiplying and dividing, pay attention to the total number of sig figs in each value in the problem. • Lowest number wins! • Ex. 12.501 5 sig figs x 0.23 2 sig figs 2.87523 = 2.9 only 2 sig figs