1. Lesson 1-4 Solving Problems with Sig Figs A Mix of Review and New Some Review: Add/Subtract and Multiply/Divide with Decimals Add/Subtract and Multiply/Divide Units Some New: Add/Subtract and Multiply/Divide with Scientific Notation

2. First… SCI vs. FLO 123.456 2 nd 4 5 SCI 1.23456 02 123.456

3. Now… Adding/Subtracting Review: Standard Notation (FLO) –Line up the Decimals in the Starting Numbers and get an unrounded “Answer” –Then “Round”… Round the answer to the same significant figures as the least number of decimals in the starting numbers. I call the rounding step “reading your keys” – just like sports plays

4. Calculator Practice Review: Standard Notation Line up the decimals 3.2 + 4.44 7.64 round = 7.6 45 – 3.78 41.22 round = 41

5. Calculator Practice New: Scientific Notation is similar (SCI) 2.3*10 3 + 3.5*10 4 = 3.73*10 4 round to two significant figures 3.7e4 “e” is a shorthand for EE and means *10 x On your calculator 2.3 EE3 + 3.5 EE4 = You have to round all by yourself – the calculator won’t do it for you! 2.3 03 + 3.5 04 = 3.73 04

6. Try This One… 5.46 x10 3 – 2 x10 2 = 5.26e3 rounded = 5e3

7. Multiply/Divide Decimals Review –Multiply or Divide the Starting Numbers and get an unrounded Answer –Then Read Your Keys… Identify the number of significant figures in each of the starting numbers Round the answer to the same significant figures as the starting number with the lowest sig figs

8. Calculator Practice 3.2 x 4.45 = 14.24 rounded = 14 Scientific Notation is the same process (use scientific notation mode – remember the display shows “SCI”) 45 ÷ 3.78 = 1.19047619e1 = 1.2e1 2.3*10 3 x 3.5*10 4 = 8.05e7 = 8.0e7 5.46*10 3 ÷ 2*10 2 = 2.73e1 = 3e1

9. Handling Units Review Add/Subtract Unit + Unit = More of that Unit Unit – Unit = Less of that Unit Multiply /Divide Unit x Unit = Unit 2 (squared) Unit 3 (cubed) ÷ Unit = Unit 2 (squared)

10. Practice 3 m + 3 m = 6 m 5 g – 1 g = 4 g 2 m x 2 m = 4m 2 6 m 3 ÷ 2 m = 3 m 2

11. Units are Important Just the Numbers 2x2x2=8 Numbers with Units 2ft x 2ft x 2ft =??? 8ft = a straight line 8 feet long – two giant steps in a game of “Mother May I?” 8ft 2 = a 2.828 foot square drawn on the floor in my room 8ft 3 = a 2 foot cubic box I can give my wife to ship her next sales item on eBay

12. Calculator Caution Our calculators will not automatically round answers to the proper number of significant figures – You Have to Round Them Yourself. Avoiding Confusion: Most of the time in this class we will round answers to 3 significant figures.