Significant Figures

Mathematics Basics

Significant Figures

Communicating information as values infers that something was measured. If reported correctly, how well the measurement was performed is, generally, communicated in the value reported for a single measurement.

The objective of this section is to survey significant figures rules, significant figure use in mathematical operations, and identifying when to communicate the accuracy of the measurement explicitly.

Four rules apply to reporting significant figures (sometimes called significant digits).

  1. All non-zero numbers (1, 2, 3, 4, 5, 6, 7, 8, and 9) are always significant.
  2. All zeroes between non-zero numbers are always significant.
  3. All zeroes which are successively to the right of the decimal point and at the end of the number are always significant.
  4. All zeroes which are to the left of a written decimal point and are in a number greater or equal to 10 are always significant.

Determining the Correct Number of Significant Digits


Addition and Subtraction


Look at all the numbers used and adjust your answer to the same as the least accurate number (least accurate place) added or subtracted using the rounding rules below.

Multiplication or Division


Look at all the numbers used and adjust your answer to the same as the number used with the least number of signifiant digits (least significant digits) using the rounding rules below.


Rounding

 


Scientific Notation

 


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