# Calculating percentage of uncertainty

Published on November 24, 2011

Q: What is the percentage uncertainty of 11.4 cm +- 0.1 cm?

+- 0.1/11.4 * 100% = +- 0.9 %

0.1/11.4 = .00877193

To multiply by 100 %, move the decimal point two places to the right.

= 0.0877193, round off to +- 0.9 %

Q: What is the percentage uncertainty of a measurement given as 75 +- 0.7 grams?

0.7/75 = .009, so move the decimal point two places to the right, = 0.9 %