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## Significant Figures :

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**SignificantFigures:**In science to find answers we take measurements and make calculations. The answers found can only be as precise as the measurements used to find them. So, answers are expressed using:**Significant Figures:**Are digits in measurements that are known with certainty plus one estimated digit Ensures that a calculated answer shows only as much precision as the least precise measurement Rely on the measurements taken, to determine how precise your outcome can be.**Rule #1: In measurements that do not contain a zero,**all numbers are significant. 5.14 3 sig fig Rule #2: All zeros between significant digits are significant. 7.502 4 sig fig Rule #3:.Zeroes to the left of the nonzero digit serve only as place holders and are not significant .056 2 sig fig Rule #4: In a number with digits to the right of the decimal point, zeros to the right of the last non-zero number are significant. 65.400 5 sig fig Rule #5:If the number is a count then sig. fig. is infinite. Measurements without decimal points are ambiguous and more information is needed to determine significant figures. 56 monkeys**Determining significant digits in measurements:**3.96 cm 5.0 cg 3.001 m 14pencils . 04 g 7.230 m 219.6 L 45.20 L**Significant Figures and Calculated Quantities:**Multiplication and Division: the answer must have the number of significant figures found in the measurement with the fewest significant figures. Example:**Addition and Subtraction:the answer should not have digits**beyond the last digit position common to all numbers being subtracted or added 34.67 40.08 495.87 4.5 40.006 9.5 1.567 40.0005 486.37 120.0865**3.414 sec + 10.02 sec + 58.325 sec + .00098 sec =**2.326 hr – 0.10408 hr = 10.19 m x 0.013 m = 80.23 m / 2.4 sec = 1884. kg + 0.94 kg + 1.0 kg + 9.778 kg = 2104.1 m – 463.09 m = 140.01 cm x 26.042 cm x 0.0159 cm = 4.301 kg / 1.9 cm3 = Practice: