• Share
Send to a Friend via Email

Your suggestion is on its way!

An email with a link to:

was emailed to:

Thanks for sharing About.com with others!

Discuss in my forum

Significant Figures Example Problem

Worked Significant Figures Example Problem

Significant figures aren't complicated once you learn the rules.

Justin Lewis, Getty Images
Significant Figure Example Problem

Three students weigh an item using different scales. These are the values they report:

a. 20.03 g
b. 20.0 g
c. 0.2003 kg

How many significant figures should be assumed in each measurement?

Solution

a. 4.
b. 3. The zero after the decimal point is significant because it indicates that the item was weighed to the nearest 0.1 g.
c. 4. The zeros at the left are not significant. They are only present because the mass was written in kilograms rather than in grams. The values '20.03 g' and '0.02003 kg' represent the same quantities.

In addition to the solution presented above, be advised that the correct answers to have been obtained very quickly by expressing the masses in scientific (exponential) notation:

20.03 g = 2.003 x 101 g (4 significant figures)
20.0 g = 2.00 x 101 g (3 significant figures)
0.2003 kg = 2.003 x 10-1 kg (4 significant figures)

Anne Marie Helmenstine, Ph.D.