1. Significant Figures Physical Science

2. What is a significant figure? There are 2 kinds of numbers: –Exact: counting objects, or definitions. –Approximate: weight, height— anything MEASURED. No measurement is perfect.

3. When to use Significant figures When a measurement is recorded only those digits that are dependable are written down.

5. When to use Significant figures If you measured the bolt you might record 6.3cm. To a mathematician 6.3, or 6.3000 is the same. Is it okay to say the bolt is 6.3000 cm long?

6. But, to a scientist 6.3cm and 6.3000cm is NOT the same 6.3000cm to a scientist means the measurement is accurate to within one ten thousandth of a cm!

7. If you used an ordinary ruler, the smallest marking is the mm, so your measurement has to be recorded as 6.3cm. But, to a scientist 6.3cm and 6.3000cm is NOT the same

8. Significant Figures …are those digits that carry meaning contributing to the precision of a measurement. The more sig fig’s, the more precise the measurement.

9. How do I know how many Sig Figs? Rule 1: All non zero digits are significant.

10. How do I know how many Sig Figs? Rule 2: If zeros are between non-zero digits, the zeros are significant. 450003 60.0301

11. How do I know how many Sig Figs? Rule 3: Zeros after the decimal AND at the END of the number are also significant. 45.0 0.30400

12. How do I know how many Sig Figs? Rule 4: Zeros are NOT significant if… -they are at the end AND before the decimal 12000 15030

13. How do I know how many Sig Figs? Rule 4: Zeros are NOT significant if… -they are at the beginning 0.12.00015030

14. How many sig figs? 7 40 65000 7,000,000 0.5 1 1 2 1 1

15. How many sig figs? 700 701 0.5003 70100 32.004 7,000,001 1 3 4 3 5 7

16. How many sig figs here? 1.2 2100 56.76 4.00 0.0792 7,083,000,000 2 2 4 3 3 4

17. How many sig figs here? 3401 2100 2100.0 5.00 0.00412 8.020 x 10 12 4 2 5 3 3 4

20. What about calculations with sig figs? Rule: When adding or subtracting; determine which measurement’s sig figs end in the largest place, (tens, ones, tenths, etc.), then round of your answer to that place.

21. Add/Subtract examples 2.45cm + 1.2cm = 3.65cm, Round off to = 3.7cm 7480cm + 2200cm = 9680 Round to  9700cm

22. Multiplication and Division Rule: When multiplying or dividing, the answer can only have as many sig figs as the measurement that has the fewest amount of sig figs.

23. A couple of examples 56.78 cm x 2.45cm = 139.111 cm 2 Round to  139cm 2 75.8cm x 9.6cm = 727.68cm 2 730cm 2 Round to 

24. The End Have Fun Measuring and Happy Calculating!