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Metric System Metric conversions Accuracy Precision Dimensional Analysis Scientific Notation Significant Figures Significant Figures in Calculations Rounding using Significant Figures Density
Addition and Subtraction
Your calculated value cannot be more precise than the least precise quantity used in the calculation. The least precise quantity has the fewest digits to the right of the decimal point. Your calculated value will have the same number of digits to the right of the decimal point as that of the least precise quantity. Example
ex.
Remember to follow the order of operations. Be sure to remember to include only the sig. figs. before going on to the next operation.
Sometimes significant figures are 'lost' while performing calculations. For example, if you find the mass of a beaker to be 53.110 g, add water to the beaker and find the mass of the beaker plus water to be 53.987 g, the mass of the water is 53.987-53.110 g = 0.877 g
There are different methods which may be used to round numbers. The usual method is to round numbers with digits less than '5' down and numbers with digits greater than '5' up (some people round exactly '5' up and some round it down). Example: In some instances numbers are truncated, or cut short, rather than rounded to obtain appropriate significant figures. In the example above, 1.549 g could have been truncated to 1.54 g.
Sometimes numbers used in a calculation are exact rather than approximate. This is true when using defined quantities, including many conversion factors, and when using pure numbers. Pure or defined numbers do not affect the accuracy of a calculation. You may think of them as having an infinite number of significant figures. Pure numbers are easy to spot, because they have no units. Defined values or conversion factors, like measured values, may have units. Practice identifying them! Example:
Metric System Metric conversions Accuracy Precision Dimensional Analysis Scientific Notation Significant Figures Significant Figures in Calculations Rounding using Significant Figures Density |