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Significant figures. Significant figures: What are they and why do they matter?. Importance: to ensure the accuracy of our measurements To make sure we tell others only what we actually know based on our equipment and it’s limitations
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Significant figures: What are they and why do they matter? • Importance: to ensure the accuracy of our measurements • To make sure we tell others only what we actually know based on our equipment and it’s limitations • Significant figures: all the numbers actually measured plus one that is estimated
Rules for significant figures • Non zeros are always significant: • 1.23456 has 6 sig figs • Zeros within a number are always significant. Both 4308 and 40.05 contain four significant figures. • Zeros that do nothing but set the decimal point are not significant. • 470,000 has 2 significant figures. • 0.00000000098 has 2 sig figs • Trailing zeros that aren't needed to hold the decimal point are significant. • 4.00 has 3 significant figures. • 0.0000050 has 2 significant figures
Rules for addition and subtraction of significant figures • The number of decimal places in the answer is equal to the number of decimal places in the quantity with the smallest number of decimal places • 1 . 2 3 + 4 . 5 6 7 = 5 . 8 0
Rules for multiplication and division of significant figures • The LEAST number of significant figures in any number of the problem determines the number of significant figures in the answer. • 2 x 10.0 = 20 • 66 / 2 = 33 = 30