Chapter SR9, Problem 24P

Solution

To perform the calculation $\text{1540 pounds}-\text{160 pounds}-\text{85 pounds}$ and write the answer with appropriate number of significant digits.

  $1300\text{ pounds}$

Given:

The expression, $\text{1540 pounds}-\text{160 pounds}-\text{85 pounds}$ .

Concept Used:

Significant digits

• All nonzero digits are significant.
• All zeros that appear between two nonzero digits are significant.
• For a decimal, all zeros that appear after the last nonzero digit are significant.
• The number of significant digits in the result of basic algebraic operations between two numbers is as many significant digits as the least number of significant digits in any of the numbers involved.

Calculation:

Note that there is 3 significant digits in 1540, 2 significant digits in the number 160, and 2 significant digits in 85, so the final answer should have 2 significant digits as shown below

  $\begin{array}{c}1540-160-85=1295\\ =1300\text{ pounds}\end{array}$

Thus, the simplified expression with appropriate significant digits is $1300\text{ pounds}$ .