Question

81.6 and 5.1 are two measured quantities and it is desired to find value of $\sqrt{\frac{81.6}{5.1}}$. The result should be expressed as:

• A. 4.000
• B. 4.00
• C. 4.0
• D. 4

Answer 1

Answer: (C)

4.0

Answer 2

Any mathematical operation like squaring; square root etc. cannot affect the number of significant digits in the result. Or in other words mathematical operations can neither increase or decrease accuracy of any measurement. Therefore answer in this case should be expressed in two significant digits which are equal to the minimum significant digits contained by any participating quantity, (in this case by number 5.1).