You measure the radius of a wheel to be 4.16 cm. If you multiply by 2 to get the diameter, should you write the result as 8 cm or as 8.32 cm? Justify your answer.
Remarks: Each of the digits of a number that are used to express it to the required degree of accuracy, starting from the first nonzero digit is known as significant figure. The least number of significant figures in any number of the problem determines the number of significant figures in the answer.