1. SWBAT describe the difference between exact & approx. values using rounding, significant figure, estimation and % error in writing by completing a set of problems.

2. Homework Integer NumbersRational Numbers

3. What’s the difference between an approximate and an exact value? What are some examples of approximate values? What are some ways we approximate?

4. Rounding Approximating a number to a certain degree or accuracy How to Round: – Go to the digit after the one to which we are rounding. – If it’s a 5 or more round up. – Less then 5 round down to zeros or – If decimal drop the zeros.

5. Rounding Lingo Rounding to the nearest ____ is the same as the rounding the nearest multiple of ____ Ex: Round to the nearest multiple of 100 Rounding to a number correct to ___ decimal places is the same as rounding to the nearest blank. Ex: Rounding a number correct to three decimals places is the same as the nearest thousandth

6. Rounding Practice Exerices 1H on page 15 – #1-3, 5

7. Important Sig Fig Note! When doing multi-step calculations (as you usually do), use at least one more sig fig that is required at the end of the problem to maintain accuracy. Ex: If the problem required 3 sig figs at the end, use four or more sig figs through out your calculation. Then round to 3 sig figs at the end.

8. Estimation An approximation usually used to check if an answer is reasonable and makes sense. Round all numbers in a calculation to 1 sig fig before completing the calculation. Ex: Jonny’s restaurant bill is 39.80 for him and his date tonight. He wants to impress her and leave over an 18% tip. How much should he leave?

9. Estimation Practice: Exercises 1K on pg 19-20 #1-7

10. Percentage Errors The difference between the estimated value and the exact value – In science it can be the difference between the theoretical value and the experimental value “Hey, when I did the Millikan Oil Drop I calculated as 1.3 x 10 -18 C. My percent error is going to be HUGE!!!”

11. Calculating the Error Take the difference between an estimate or approximate value and the exact value Error = v a – v e V a = appoximate value V e = exact value

12. Percentage Error Formula

13. Homework: Pg 18 Ex 1J Pg 21 Ex 1L