Adding and Subtracting with Significant Figures

This video tutorial explains how to handle significant figures in chemistry, focusing on addition and subtraction. It outlines three key rules: aligning decimal points, performing the operation, and ensuring the result has the same number of decimal places as the measurement with the fewest. An example problem is provided, demonstrating these rules. A shortcut is also introduced, allowing quick identification of the correct answer by counting decimal places. The video concludes with a call to subscribe for more content.

Why are significant figures important in chemistry?

• They are necessary for naming chemical compounds.

• They are used to determine molecular weights.

• They ensure precision in measurements and calculations.

• They help in balancing chemical equations.

What is the first rule to follow when adding or subtracting with significant figures?

• Round off the numbers first.

• Line up the decimal points.

• Count the total number of digits.

• Convert all numbers to scientific notation.

Which step is typically done by the calculator when adding or subtracting with significant figures?

• Counting the significant figures.

• Ensuring the sum has the correct number of significant figures.

• Rounding off the final result.

• Lining up the decimal points.

How many digits after the decimal point should the sum have if the measurements are 6.6412, 2.34, 3.456, and 7.89?

• 2

• 3

• 1

• 4

What should you do if the next digit after the required significant figures is 5 or greater?

• Ignore the digit.

• Round the prior digit up.

• Leave the digit as it is.

• Add an extra digit.

What is the shortcut for determining the correct number of significant figures in addition and subtraction?

• Convert all numbers to scientific notation.

• Use the measurement with the fewest digits after the decimal point.

• Use the measurement with the most digits after the decimal point.

• Count the total number of digits.

When does the shortcut for significant figures not work?

• When subtracting instead of adding.

• When there are more than 2 measurements.

• When the numbers are in scientific notation.

• When there is more than one choice with the fewest digits after the decimal.

What should you do if there is more than one choice with the fewest digits after the decimal?

• Calculate and round correctly.

• Choose the one with the least significant figures.

• Ignore the decimal points.

• Choose the one with the most significant figures.

What is the correct answer if the sum of the measurements is 20.327 and the measurement with the fewest digits after the decimal point has 1 digit?

• 20.3

• 20.32

• 20.33

• 20.327

What should you do if you found the video helpful?

• All of the above.

• Give it a thumbs up.

• Leave a comment.

• Subscribe to the channel.