1. Significant Figures!
A.K.A. Sig. Figs.

2. Actual measured #’s, not placeholders Two techniques:
Numbers with decimals
Numbers without decimals

3. Zero's in front of the number do not count.
NUMBERS WITH DECIMALS
Zero's in front of the number do not count.
All other digits including the ZERO’S at the end are significant!

4. PRACTICE #1
100.0
0.002
2.04
= 4
= 1
= 3
= 5

5. NUMBERS WITHOUT DECIMALS
All digits count except 0’s at the end.
Sandwiched zeros count!

6. PRACTICE #2
= 3
= 1
= 4
154
100
10000
65010

7. PRACTICE #3
= 5
= 3
1000.0
10001
1.00 x 105
4.24 x 107

8. SUMMARY 0’s in front don’t count No decimal? 0’s in back don’t count
Sci. Not.? All digits count!

9. From now on put all answers into scientific notation!
Your answer: 100
Only 1 sig fig!
1.00 x 102
From now on put all answers into scientific notation!