![]() For every measurement made using an instrument, the last digit capable of being read is going to be an estimate. The precision of the reading is limited by the gradation of the scale and by the width of the lines marking the boundaries. Determining the Number of Significant Figures Most measurements made in the laboratory involve the reading of some scale. This means that if you multiplied or divided three numbers: 2.1, 4.005 and 4.5654, the value 2.1 which has the fewest number of digits would mandate that the answer be given only to two significant figures.Appendix A: Significant Figures 1. In multiplication and division the number of significant figures is simply determined by the value of lowest digits. ![]() Significant Figures and Multiplication or Division Specifically this means the number of digits after the decimal determine the number of digits that can be expressed in the answer. In addition and subtraction the number of significant figures that can be reported are based on the number of digits in the least precise number given. Significant Figures and Addition or Subtraction The application of significant figures rules while completing calculations is important and there are different ways to apply the rules based on the type of calculation being performed. Below are the rules to follow when doing this: In order to present a value in the correct number of significant digits you will often have to round the value off to that number of digits. By definition, the value is 299,792,458 meters per second. Interestingly, the speed of light is now a defined quantity.Therefore, if a number is exact, it DOES NOT affect the accuracy of a calculation nor the precision of the expression. Another example of this are defined numbers, such as Exact numbers are counting up how many of something are present, they are not measurements made with instruments. A final zero or trailing zeros in the decimal portion ONLY are significant.Įxact numbers, such as the number of people in a room, have an infinite number of significant figures.Any zeros between two significant digits are significant.Non-zero digits are always significant.There are three rules on determining how many significant figures are in a number: Moving the decimal point to the right yields a negative exponent.Īnother reason we often use scientific notation is to accommodate the need to maintain the appropriate number of significant figures in our calculations. So to summarize, moving the decimal point to the left yields a positive exponent. The first non-zero digit is 5 so the number becomes 5.56 and we had to pass the decimal point by 4 digits to get it to the point where there was only one non-zero digit at the front of the number so the exponent will be -4. The exponent then equals the number of digits you had to pass along the way. You simply move the decimal to the right until only one non-zero digit is in front of the decimal point. Small numbers can be converted to exponential notation in much the same way. ![]() The resulting exponential number is then: ![]() …and thus the exponent we place on the power of 10 is 5. In this number we move the decimal point 5 times. To convert this to an exponential number we need to move the decimal to the left until only one digit resides in front of the decimal point. This is a large number and the implied decimal point is at the end of the number. How to convert non-exponential numbers to exponential numbers: Ex: 1.22 x 10 3įor a number to be in correct scientific notation only one digit may be to the left of the decimal. …consists of two parts: A Number and a Power of 10. …is most often used in "scientific" calculations where the analysis must be very precise ![]() …is a way to express very small or very large numbers In the previous example you should have noticed that the answer is presented in what is called scientific notation. ![]()
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