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Question
The radius of a circle is stated as 2.12 cm. Its area should be written as
Options
14 cm2
14.1 cm2
14.11 cm2
14.1124 cm2
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Solution
14.1 cm2
Area of a circle, A= \[\pi r^2\] On putting the values, we get:
\[A = \frac{22}{7} \times 2 . 12 \times 2 . 12\]
\[ \Rightarrow A = 14 . 1 {cm}^2\]
The rules to determine the number of significant digits says that in the multiplication of two or more numbers, the number of significant digits in the answer should be equal to that of the number with the minimum number of significant digits. Here, 2.12 cm has a minimum of three significant digits. So, the answer must be written in three significant digits.
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