Math is the language of the universe, and no one speaks that language better than science. Data and numbers are the essence of science, but not all data is good or usable. Data has to be precise and accurate.

Precision and accuracy are essential when it comes to the reliability of experimental data. Now, what exactly do these two words mean.The definition of precision is how close data and measurements are from each other. While the definition of accuracy is how close data and measurements are from the true value.

http://dl.clackamas.cc.or.us/ch104-01/accuracy_vs_precision.htm

Significant numbers play a big part in the accuracy of measurements. Significant numbers are important because they tell us how accurate the numbers we use are.

http://www.esu.edu/~scady/measurement.shtml

For example the numbers:

**100 grams, ****100. grams, ****100.00 grams**

100 gram has only one significant figure and that’s 1. Since this digit is placed in the hundreds place, the measurement given is only accurate to the nearest 100 grams. This means that it is closer to 100 grams than 200 or 0 grams. 100. grams has three significant figures because of the decimal. Since the last significant figure is in the ones place, the number is accurate up to a gram. Meaning the number is closer to 100 grams than a 101 or 99 grams. 100.00 grams has five significant figures because the last significant figure is in the hundredths place. this number is now accurate to the nearest 0.01 grams. Meaning the number is closer to 100.00 grams than 100.01 or 99.99 grams. Significant number overall tell us how good and accurate or data is. For a more detailed explanation watch this video http://www.youtube.com/watch?v=eCJ76hz7jPM.

Without precision people question whether or not the experiment can be reciprocated again with the same numbers. Without accuracy experiments are disregarded because measurements do not hold true to their actual values.

Recently, the atomic masses for nineteen elements changed to more accurate values. This was done through more precise measurements of the abundance of isotopes. The changes might have been extremely small but serve great purpose in high-precision measurements. These numbers are used to measure the reliability of laws of nature such as E=mc^2. That is why the precision and accuracy of data in experimentation is crucial.

sources:

http://misterguch.brinkster.net/sigfigs.html

http://dl.clackamas.cc.or.us/ch104-01/accuracy_vs_precision.htm

http://www.livescience.com/39912-atomic-weight-changed-for-19-elements.html