Significant Figures are the digits of a number which are used for expressing the necessary degree of accuracy that starts from the first non-zero digit.

The number of significant figures in a result indicates the number of digits that can be used with confidence. The idea of a significant figure is simply a matter of applying common sense when dealing with numbers. An important characteristic of any numerical value is the number of digits, or significant figures it contains. A significant figure is defined as any digit in the number ignoring leading zeros and the decimal point.

Examples of Significant Figures

  • 821 has 3 significant figures
  • 0.0310 has 3 significant figures

The digits that are used to express a number are called significant digits or significant figures. The use of significant figure is very important.

“Significant figures is the number of digits in a number that actually convey any meaning. This does not include any information on the order or power of ten in the number representation, as this can be conveyed by other means.”
The term "significant figure" refers to the number of digits in a written number that can be trusted by implication. Factors that can reduce trust include the possibility of round-off errors and any explicit expression of uncertainty. Unless specified otherwise, all digits in a written number are considered significant. Also, whole numbers generally have an infinite number of significant figures unless uncertainty is expressed explicitly.