What is the number of significant digits in 20,300.011 lb?

1 Answer
Jun 16, 2017


Given: #20,300.011# lb. This is a measurement.

Significant figures (SF) is all about accuracy of a measurement. The significant figures = the number of certain digits + 1 uncertain digit. If you are measuring a small object with a ruler in millimeters, you are accurate to 1 mm. The uncertainty comes when you try to estimate the fraction of 1 mm.

For example: You measure the object to be 6.5 mm. The 0.5 mm is the uncertain measurement. Someone else might say it is actually 6.7 mm.

The rules for figuring out the number of significant figures based on a measurement that someone else measured are as follows:

  1. Every nonzero digit in a measurement is considered significant.
    Ex. #714# m has 3 SF

  2. Every zero between nonzero digits are significant.
    Ex. #7003# m has 4 SF

  3. Leftmost zeros appearing in front of nonzero digits are not significant.
    Ex. #0.0071 m = 7.1 xx 10^(-3)# has 2 SF

  4. Zeros at the end of a measurement and to the right of a decimal are always significant.
    Ex. #43.000# has 5 SF

According to the rules: #20,300.011# lb has 8 SF