Uncertainty of 2500.0 g: tenths place QUESTION: To how many significant figures should the result of the following calculation be reported? 2500.0 g + 25 g A. 2, B. 3, C. 4, D. 5 Rule for addition or subtraction: last sigfig location in the answer is same as in the term with the larger uncertainty. Location of last sigfig implies magnitude of uncertainty. Uncertainty of 2500.0 g: tenths place Uncertainty of 25 g: ones place [Larger] Therefore: last sigfig in answer is in ones place. 2525.0  2525 g SCRIPT To how many significant figures should the result of the following calculation be reported? Two thousand five hundred point zero grams Plus Twenty five grams. CLICK When adding or subtracting numbers, the location of the last significant digit in the answer must be the same as that in the term with the larger uncertainty. In this case, let’s examine the terms that we’re adding. The last significant digit in two thousand five hundred point zero grams is in the tenths place. HIGHLIGHT 0 in tenths place This means that the magnitude of the uncertainty in 2500.0 grams is in the tenths place. For twenty five grams, the last significant digit is in the ones place. HIGHLIGHT 5 in 25. This means that the magnitude of the uncertainty in 25 grams is in the ones place. Since the ones place is larger than the tenths place., the last significant figure in the answer should be in the ones place. The answer should be reported as two thousand five hundred twenty five grams. There are four significant figures in the answer…2…5…2…and 5. The correct answer is 4. PAUSE 2 seconds END RECORDING

Video ID: 1A-4-3 © 2008, Project VALUE (Video Assessment Library for Undergraduate Education), Department of Physical Sciences Nicholls State University Author: Glenn V. Lo Funded by Louisiana Board of Regents Contract No. LA-DL-SELECT-13-07/08