1. Significant Figures & Scientific Notation

2. Rules for SigFigs Any non-zero digit is significant
Any trapped zeros are significant
Zeros to the left of the decimal point at the end of a number are NOT significant (trailing zeros)
Zeros to the right of the decimal point at the beginning of a number are NOT significant (leading zeros)
Answer can have only as many sigfigs as the fewest in the problem

3. EXAMPLES 23 – both are non-zero numbers (2 sigfigs)
109 – zero between two non-zero numbers (trapped zero – 3 sigfigs)
4500 – trailing zeros before the decimal are NOT significant (2 sigfigs)
– leading zeros after the decimal are NOT significant (3 sigfigs)
6.00 – trailing zeros after the decimal ARE significant (3 sigfigs)

4. Scientific Notation Can be only 1 number to the left of the decimal
Second part is written as (x 10n)
If the number to be written is smaller than 1 then n MUST be negative
If the number to be written is larger than 1 then n MUST be positive

5. EXAMPLES Write the following in scientific notation:
157 – move decimal two places to left
1.57 x 102
23000 – move decimal four places to left
2.3 x 104
– move decimal five places to right
2.79 x 10-5
– move decimal ten places to right
3.24 x 10-10