Significant Figures
When measuring with any device, you should read all of the possible digits on the measuring device known with certainty, and then you should add one uncertain digit. The very last number in any measurement is the uncertain digit. Scientists indicate the uncertainty in a measurement by using the correct number of significant digits. In this interactivity, click on each of the tabs to learn how to determine the number of significant digits in a measurement.
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Calculations with Significant Figures
Now that you know how to determine the number of significant figures in a number, consider how these figures interact in calculations. When calculating with measurements, your resulting answer can only be as accurate as your least accurate measurement. Follow these two rules:
- Rule 1
When multiplying and dividing with measurements, your least accurate measurement is the one with the least number of significant figures. - Rule 2
When adding and subtracting with measurements, your least accurate measurement is the one with the least number of decimal places.
Sometimes you will need to round your answer to the correct number of significant figures. When rounding off numbers, round the preceding digit up when the digit to be removed is five or greater. When the digit to be removed is less than five, round the preceding digit down.
Scientific Notation
When working with very small or very large numbers, chemists often use a numeric shorthand called scientific notation. Scientific notation utilizes multiples of ten to simplify complex numbers. When counting the number of significant figures in a measurement with scientific notation, the number of significant figures is determined by the coefficient of the number. View this presentation to learn more about scientific notation.
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Significant Figures Review
Now that you have explored using significant figures and scientific notation in chemistry, review your knowledge in this non graded activity. Read each question and select the correct answer. Then, click SUBMIT to check your response. Click the interactivity thumbnail and then click NEXT to get started.