Significant figures

Definition

Significant figures are the digits in a measurement that carry meaningful information about its precision. They include all certain digits plus one uncertain or estimated digit.

5 Must Know Facts For Your Next Test

1. Zeros between non-zero digits are always significant.
2. Leading zeros (zeros to the left of the first non-zero digit) are never significant.
3. Trailing zeros in a decimal number are significant.
4. In multiplication and division, the number of significant figures in the result should match the number with the fewest significant figures used in the calculation.
5. In addition and subtraction, the result should be rounded to match the least precise measurement (the one with the fewest decimal places).

Review Questions

• How do you determine which digits are considered significant in a given measurement?
• What is the rule for determining significant figures when multiplying or dividing numbers?
• Why is it important to consider significant figures when performing calculations in chemistry?

Related terms

Accuracy:

A measure of how close a measurement is to the true value.

Precision:

A measure of how close repeated measurements are to each other.

Measurement Uncertainty: An estimate of the amount by which a measured value may differ from the true value.