Problem
Unrounded
answerAnswer rounded to the correct number of significant
figures4.29 cm × 3.24 cm
=
13.8996 cm^2 =
13.9 cm^2Explanation: Both measured quantities have three significant figures. Therefore,
the answer should be rounded to three significant figures.
Example 2
Problem
Unrounded
answerAnswer rounded to the correct number of significant
figures4.29 cm × 3.2 cm
=
13.728 cm^2 =
14 cm^2Explanation: One of the measured quantities has only two significant figures.
Therefore, the answer should be rounded to two significant figures.
Example 3
Problem
Unrounded
answerAnswer rounded to the correct number of significant
figures8.47 cm^2 /4.26 cm
=
1.9882629 cm =
1.99 cmExplanation: Both measured quantities have three significant figures. Therefore,
the answer should be rounded to three significant figures.
Second, when adding or subtracting measured quantities, the sum or
difference should be rounded to the same number of decimal places as the
quantity having the least number of decimal places.
Example 1
Problem
Unrounded answer
Answer rounded to the correct number of significant figures3.56 cm^