01.07 Accuracy and Precision: Determining Significant Figures—Text Version

Now it is time to try some calculations on your own. Calculate the answer to each question and enter it below.  Remember to round your answer to the correct number of sig figs.

Question 1:
6.821 meters + 1.4 meters plus 1.05 meters

Question 2:
26.50 grams ÷ 9.67 milliliters

Question 3:
Convert 17.8 m/s to the unit k/hr.

Question 4:
12.50 kilograms—17.80 kilograms + 13.0 kilograms

Check your answers:

Question 1:
6.821 meters + 1.4 meters plus 1.05 meters

Answer
9.3 meters because the measurement 1.4 meters only has one place after the decimal, the answer 9.27 one must be rounded to have only one place after the decimal.

Question 2:
26.5 zero grams ÷ 9.67 milliliters

Answer
2.74 g/mL because 9.67 milliliters only has three sig figs total while 26.5 zero grams has four, the final answer must have three sig figs total.

Question 3:
Convert 17.8 m/s to the unit k/hr.

Answer
× × × = 64.1 km/hr.

17.8 meters has three sig figs, so the answer 64.08 must be rounded to three sig figs—64.1 kilometers per hour

Question 4:
12.500 kilograms—17.80 kilograms + 13.0 kilograms

Answer
7.80 kilograms because the measurements 17.80 kilograms and 13.0 kilograms only have two places after the decimal while 12.500 kilograms has three places after the decimal. So, a zero must be added to the end of the answer to give it the necessary two places after the decimal.