* Accuracy is correctness. For example, if a coin has a mass of grams, these would all be accurate masses: 10 g, 10.1g, g, g But an inaccurate mass would be 25 grams. * Precision is exactness. Precision comes from the type of measuring tool you use.

100-meter butterfly results in the 2008 Olympics: Michael Phelps seconds Milo Cavic seconds What if both stopwatches read 51 seconds? They would be accurate, but not sufficiently precise.

Sig Figs measure the degree of precision of a measurement.

In science, a correctly precise measurement includes all digits that are known for sure, plus a digit that is estimated.

The correctly precise measurement for the ruler on the left is 1.5 inches. However, the correctly precise measurement for the ruler on the right is 1.48 inches.

* If you’re using a measuring device with a digital display, (like an electronic balance), the rounding has already been done for you. Be sure to copy down every decimal place shown on the digital display.

There are ONLY two rules to remember when counting the # of Sig Figs.

* Rule #1: Don’t start counting till you get to a number that isn’t a zero. * Rule #2: Once you start counting, don’t stop till you’ve counted all the digits, including zeroes

Where is the Atlantic Ocean, and where is the Pacific Ocean?

Is the decimal point present or absent? Ask yourself:

Count from first non-zero number starting at the Pacific side Once you start counting, you don’t stop!

Is the decimal point present or absent? 18,000,000

Count from first non-zero number moving from the Atlantic side. 18,000,000

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For multiplication and division

You and your lab partner, Sloppy Joe, have been assigned to find the area of your lab table. You carefully measure the length, and find it to be cm. Sloppy Joe glances at the width and suggests that it measures about 100 cm.

x 100 = S.F.1 S.F.5 S.F.? Answer must be recorded as 20,000 It can have only one sig fig.

Your answer MUST have the same number of sig figs as the factor with the least number of sig figs.

610 x 6.20 = S.F.3 S.F. What is the correct answer? 3800

Your answer can not contain more decimal places than the least precise measurement.

Line up the decimal points in the numbers =????

Answer stops here

The number written before the times sign shows the correct number of SIG FIGS. Ex: x sig figs

3.50 x S.F. 5.0 x S.F. 3 x S.F.