Chapter 3:Sig Figs

Today in class, we begin our new unit on Sig figs. So what are Sig figs and why do we need them?


Sig figs
-They are meaningful values that are accurate.

- They can also be precise if there are many of them

-We need them to get precise accurate measurements and not just approximating

Eg.24.37, 24.5, 35.3

"Watch this video if you did not listen in class. It is very helpful trust me"

More Practice problems go to:http://science.widener.edu/svb/tutorial/sigfigures.html

Rules to Significant Numbers

-Non-zero digits are always significant eg.23490.33

-All final zeros after the decimal point are significant eg 95.000

-Zeros between two other significant digits are significant. eg 1.00009

-Zeros used solely for spacing the decimal point are not significant. eg.0.00009

Rounding Rules For Sig Figs

"When Adding Sig figs you always round to the nearest Decimal"



"When dividing and multiplying Sig Figs you always round to the fewest Sig figs in this case 2"



Exact Numbers

Today we also learn about exact numbers which are numbers that cannot be round up because it is exact.

Eg.
-1 km will always=1000 meters
-2 cats will always be 2 cats. There cannot be 1.9 cats
-1 human will always be 1 human. Not 0.99

Two cats will always be 2 cats not 1.999!!!!!!!!!!!!!!!

• Look for numbers to the right of the digit to round up
• If the digit is less than 5, the number does not change
• If the digit is more than 5, the number rounds up
• If the digit is exactly 5, than round the digit to make it an even number like 4,6,8,2.
• If the digit is the number 5 and there are more no zero digits after five than round the number up.