Report the result of the following calculation to the correct number of significant figures.

c)

Answer

This problem is more complicated since we must perform a subtraction, followed by a division, followed by an addition. We must do each step and each time pay careful attention to the number of significant figures.

Step 1): the subtraction

Since each number has three places to the right of the decimal our answer has three places to the right of the decimal. We are not concerned with number of significant figures in our answer, ONLY with the number of places to the right of the decimal. Now the division,

Step 2): the division

After performing the division we must decide how many significant figures to report in our result. Since the numerator has two significant figures and the denominator has five significant figures our answer can only be reported to two significant figures.

Now we can round this number to two significant figures,

Step 3): the addition

So we've performed the addition now we must determine the answer to the correct number of significant figures. In addition and substraction our answer can have no more digits to the right of the decimal as the the number with the smallest number of digits to the right of the decimal. The number 0.00061 has five digits to the right, while the number 2.091 has three digits to the right. So our answer can only have three digits to the right of the decimal.

So we must round off the result. Since the number '6' is the left most digit to be dropped we will add '1' to the last digit retained. The correct answer is 2.092.