# Exam

Topics: Significant figures, Economics, David Ricardo Pages: 3 (928 words) Published: June 17, 2013
Measurement (from Old French, mesurement) is the assignment of numbers to objects or events.[1] It is a cornerstone of most natural sciences, technology, economics, and quantitative research in other social sciences. Having an international standard allows scientists and other people to share information easily. For example, if a chemist discovers something, he or she will want to share their findings with other chemists. These other chemists will want to test the theory through whatever experiment he or she had used. So it's important that they are using the same exact measurements when repeating the experiment elsewhere, otherwise the results will be drastically different. The significant figures (also known as significant digits in American English, and often shortened to sig figs or sig digs) of a number are those digits that carry meaning contributing to its precision. This includes all digits except: * Certain leading and trailing zeros which are merely placeholders to indicate the scale of the number. (Exact rules are explained in the section "Identifying significant figures".) * Spurious digits introduced, for example, by calculations carried out to greater precision than that of the original data, or measurements reported to a greater precision than the equipment supports. Significance arithmetic are approximate rules for roughly maintaining significance throughout a computation. The more sophisticated scientific rules are known as propagation of uncertainty. Numbers are often rounded to avoid reporting insignificant figures. For instance, if a device measures to the nearest gram and gives a reading of 12.345 kg, it would create false precision to express this measurement as 12.34500 kg. Numbers can also be rounded merely for simplicity rather than to indicate a given precision of measurement, for example to make them faster to pronounce in news broadcasts. Arithmetic precision can also be defined with reference to a fixed number of decimal places...