Significant figures, also known as significant digits, are the digits in a number that carry meaning contributing to its measurement accuracy and precision. They include all non-zero digits, any zeros between significant digits, and trailing zeros in the decimal portion. Significant figures are crucial in scientific and technical measurements to convey how precisely a value is known.
Key Points on Significant Figures
- All non-zero digits are significant. For example, 652.1 has 4 significant figures.
- Zeros between non-zero digits are significant, such as 4005 which has 4 significant digits.
- Leading zeros to the left of the first non-zero digit are not significant, e.g., 0.003 has 1 significant figure.
- Trailing zeros after a decimal point are significant, like 7.00 having 3 significant figures.
- Trailing zeros in a whole number without a decimal point may or may not be significant depending on context (e.g., 2650 could have 3 or 4 significant figures depending on measurement).
Importance of Significant Figures
They indicate the precision of a measurement: all digits known with certainty plus one estimated digit. Correct use of significant figures ensures reliability and clarity in reporting measurements and performing calculations by reflecting the precision afforded by the measuring instrument or the data given.
Summary
Significant figures help measure and communicate the accuracy of a number by including all digits that are known reliably plus one estimated digit. They are determined by a set of simple rules centered on which digits are considered meaningful in the number's notation.
