Significant Figures and Measurement Precision

If you multiply 4.2 (which has two important numbers) by 2.00 (which has three important numbers), how many important numbers should your answer have?

• One

• Two

• Three

• Four

A scientist measures the length of a table as 1.5 meters (2 important numbers) and its width as 0.80 meters (2 important numbers). If they multiply these to find the area, how many important numbers should be in the area measurement?

• One

• Two

• Three

• Four

When adding 5.12 (two digits after the decimal) and 3.4 (one digit after the decimal), how many digits should be after the decimal point in your final answer?

• One

• Two

• Three

• Zero

A baker adds 25.5 grams of flour (one digit after the decimal) to 10.25 grams of sugar (two digits after the decimal). How many digits should be after the decimal point in the total weight of the ingredients?

• One

• Two

• Three

• Zero

A scientist measures two pieces of string. One is 1.901 meters long, and the other is 2.09 meters long. If the scientist puts them together, what is the total length, keeping in mind how precisely each was measured?

• 3.991 meters

• 3.99 meters

• 4.0 meters

• 3.9 meters

When you add or subtract measurements, how do you decide how many decimal places your final answer should have?

• The answer should have the most decimal places from the original measurements.

• The answer should have the fewest decimal places from the original measurements.

• The answer should always have two decimal places.

• The number of decimal places does not matter.

When adding two measurements, 5.25 cm and 10.3 cm, which measurement helps you decide how many decimal places your answer should have?

• 5.25 cm

• 10.3 cm

• Both measurements

• Neither measurement

A builder measures a building to be 350 feet tall (measured to the nearest 10 feet). They add a small antenna that is 8 feet tall (measured to the nearest 1 foot). What is the total height of the building with the antenna, considering the precision of the measurements?

• 358 feet

• 350 feet

• 360 feet

• 300 feet