1. 30 AUGUST 2013 Significant Figures Rules

2. Precision When completing measurements and calculations, it is important to be as precise as possible.  Precise: the ability in measurements to obtain close to the same measurement repeatedly

3. Significant Figures Significant figures are the digits in a number that carry meaning in terms of precision. For example, 0.906 The digits 9, the second 0, and 6 are significant, but the 0 before the decimal is not. But why?

4. Rules 1. Any digit between 1 and 9 is ALWAYS significant. Ex. 765 has 3 significant figures. 2. Zeroes at the beginning of a number are NEVER significant. Ex. 0.76 has 2 significant figures.

5. Rules 2 3. Zeroes “sandwiched” between two nonzero digits are ALWAYS significant. Ex. 708 has 3 significant figures. 4. Zeroes at the end of a number are significant ONLY if there is a decimal somewhere in the number. Ex. 1.540 has 4 significant figures.

6. Rounding Often we have to round a number to have a specific number of significant figures. In order to do so, you will:  Begin at the left side of the number and identify each significant figure.  Round the digit that will become the last significant figure that you want to keep. Ex. 0.54768 has 5 significant figures. If I want to keep 3, I will round the 7, because it is the 3 rd significant figure. Because a 6 is after the 7, the 7 will round up to 8, leaving me with 0.548 as my new answer.