Oct 26, Significant Digits

After the test that I have failed, today we have learned significant digits.

Significant Digits(Figures)
-The last digit in a measurement is uncertain.
-Trailing zeros after the decimal point are counted
-Leading zeros aren't counted
-Trailing zeros without a decimal point aren't counted

Example : 2.567 = 4 significant digits
               0.0097 = 2 significant digits
               10000 = 1 significant digits
               10000. = 5 significant digits
Exact Numbers
-Same quantities are defined as exactly a certain amount and no rounding is required and have infinite significant digits
 Ex. Number of people, animals, items etc
Rounding Rules
-if the number you are rounding from is greater than 5 you round up
-if the number you are rounding from is smaller than 5 you keep the number in front
-when the number you are rounding to is 5 then:
                 -if the number you are rounding from is 5, round to make the last digit even
                 -if the number you are rounding from isn't 5 then you round up
Example:
     Rounding to the tenth
1.01 = 1.0
1.06 = 1.1
1.00 = 1.0
4.95493 = 5.0
4.85493 = 4.8
1.05 = 1.1