Significant Figures Significant figures are all the digits

Significant Figures Significant figures are all the digits of a measurement that are known with certainty, plus one uncertain digit

Rules for Sig Figs 1. Nonzero numbers are always significant Example: 38594. 4 = 6 sig fig 2. Zeros between nonzero digits are significant Example: 50503 = 5 sig fig

Rules for Sig Figs 3. Zeros in front of nonzero digits (leading zeros) are NOT significant. Example: 0. 00602 = 3 sig fig 4. Zeros are NOT significant at the end of a number unless there is a decimal Example: 4000 = 1 sig fig 4000. 0 = 5 sig fig

Sample Problems Determine the number of significant figures in the following numbers. 1)0. 078082 6) 0. 000000664 2)0. 0000027233 8 7) 45008 3)118000 4)87200 5)0. 00002786 8) 770 9) 0. 00000850 10) 74171. 7

Review of Rounding Numbers Round the following number to the number of sig figs indicated. 1. 5. 67498 - round to 1 sig fig 2. 0. 04102 - round to 3 sig figs 3. 2. 998 - round to 2 sig figs 4. 26, 384 - Round to 2 sig figs

Rounding to the correct number of Significant Figures In addition and subtraction, the result should have the same number of decimal places as the number with the LEAST number of decimal places in the problem. Example: 12. 5 (one decimal place) + 9. 65 (two decimal places) 22. 15 This is what you get when you do the math, but you will round it so it has ONE decimal place CORRECT ANSWER: 22. 2

Rounding to the correct number of Significant Figures In multiplication and division, the result should have the same number of sig figs as the number with the LEAST number of sig figs in the problem. Example: 10 (one sig fig) X 62 (two sig figs) 620 This is what you get when you do the math, but you will round it so it has ONE sig fig CORRECT ANSWER: 600

Practice Problems Add or subtract as indicated, then round to the correct number of sig figs: 1) 5. 72 + 2 2) 500 – 79. 4 3) 0. 006 + 0. 04 4) 66. 34 + 27. 008

Practice Problems Multiply or divide as indicated, then round to the correct number of sig figs: 1) 27. 3 x 4. 5 2) 4008 ÷ 3. 0 3) 0. 009 ÷ 7 4) 7. 0000 x 0. 003

Exit Ticket Using a scale from 1 -5, 1 meaning you have no clue, and 5 meaning you really get it, rate how you feel about the following: 1. Identifying the number of sig figs in a numer 2. Rounding to a certain amount of sig figs 3. Rounding to sig figs with addition/subtraction 4. Rounding to sig figs with multiplication/division