Significant Figures

# Significant Figures

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## Significant Figures

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1. Significant Figures Used to report all precisely known numbers + one estimated digit

2. Rule #1 • Every nonzero digit is significant Examples: 24 = 2 3.56 = 3 7 = 1

3. Rule #2 • Zeros between non-zeros are significant Examples: 7003 = 4 40.9 = 3

4. Rule #3 • Zeros appearing in front of non-zero digits are not significant • Act as placeholders • Can’t be dropped, show magnitude Examples: 0.00024 = 2 0.453 = 3

5. Rule #4 • Zeros at the end of a number and to the right of a decimal point are significant. Examples: 43.00 = 4 1.010 = 4 1.50 = 3

6. Rule #5 • Zeros at the end of a number and to the left of a decimal point aren’t significant Examples: 300 = 1 27,300 = 3

7. Special Rule • Always remember PA P A If a decimal point is present, start on the Pacific (P) side and begin counting at the first non-zero digit all the way to the end. If a decimal is absent, start on the Atlantic (A) side and begin counting at the first non-zero digit all the way to the end.

8. Special Rule (cont.) • Remember PA Examples: 123.003 = decimal present, start on “P” side, begin counting Answer = 6

9. Special Rule (cont.) • Remember PA Examples: 204,000 = decimal absent, start on “A” side, begin counting at first non-zero digit until you hit the end of the number. Answer = 3

10. Sig. Fig. Math Rules • Multiplication / Division: Your answer can’t have more sig. figs. than the number in the problem with the least amt. of sig. figs. Example = 60.56227892 x 35.25 Calculator says – 2134.890832 (wrong) Answer - 2135

11. Sig. Fig. Math Rules • Addition / Subtraction: Answers can’t have more numbers to the right of the decimal point than the number in the problem with the least amt. of numbers to the right of the decimal point. Example = 24.1 + 3.35 + 2.23 Calculator says – 29.68 (wrong) Answer – 29.7