Significant Figures Writing Numbers to Reflect Precision

A Since pennies come in whole numbers, 7pennies means 7.00000... permies. This is an exact number and therefore never limits significant figures in calculations. 

A Our knowledge of the amount of gold in a 10-g gold bar depends on how precisely it was measured. 

Scientific nmnbers are reported so that every digit is certain except the last, which is estimated. For example, suppose a reported measurement is  

The first four digits are certain the last digit is estimated. 

A FIGURE 2.1 Estimating tenths of a gram This balance has markings every 1 g, so we estimate to the tenths place. To estimate between markings, mentally divide the space into 10 equal spaces and estimate the last digit. This reading is 1.2 g. 

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Significant Figures Writing Numbers to Reflect Precision... 

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