These problems will help you master the rule for rounding answers to the correct number of significant figures when multiplying or dividing measurements.

Practice Problems

Solve these problems and round your final answers to the correct number of significant figures. Check your answers using the Answer Key at the bottom of the page.

Problem 1: Simple Multiplication

An object is measured to be 10.3 meters long and 1.5 meters wide. What is its area?

Problem 2: Simple Division

A car travels 350.0 kilometers in 2.5 hours. What is its average speed in kilometers per hour?

Problem 3: Multiplying with Different Precision

Calculate the volume of a rectangular prism with a length of 5.2 cm, a width of 4.10 cm, and a height of 3.001 cm.

Problem 4: Division with Zeros

The mass of a sample is 8.00 g and its volume is 2.5 mL. What is the density of the sample?

Problem 5: Multiplication with Scientific Notation

A star is located at a distance of $2.5 \times 10^3$ light-years. If a spaceship travels at a speed of $1.50 \times 10^1$ light-years per year, how long will it take to reach the star?

Problem 6: Mixed Operations

A student measures the length of a desk as 1.50 meters. They then add a stack of books with a height of 0.2 meters. What is the new total height?

Show Answer Key

Problem 1: $15 \text{ m}^2$ (The least number of significant figures is 2, from 1.5 m).

Problem 2: $140 \text{ km/h}$ (The least number of significant figures is 2, from 2.5 h. Note: the zero in 140 is a placeholder, not significant).

Problem 3: $64 \text{ cm}^3$ (The least number of significant figures is 2, from 5.2 cm).

Problem 4: $3.2 \text{ g/mL}$ (The least number of significant figures is 2, from 2.5 mL).

Problem 5: $1.7 \times 10^2 \text{ years}$ (The least number of significant figures is 2, from $2.5 \times 10^3$).

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