**Definition:** The significant figure by definition are the reliable digits in a number that are known with certainty.

- Each of the digits of a number that are used to express it to the required degree of accuracy, starting from the first non-zero digit.
- The term significant figures refers to the number of important single digits (0 through 9 inclusive) in the coefficient of an expression in Scientific notation. the number of Significant figures in an expression with which an engineer or scientist stats a quantity.
- In significant figure zero has its own importance in expressing a number sometimes it is significant and sometimes it is not a significant figure.

**Rules for Significant Figures: **

These rules will simplify it more further. Now it is easy to understand Significant Figures by these rules:

- All non-zero digits are Significant Figures e.g- 38 has two Significant Figures and 0.38 has also two Significant Figures.
- If zero comes in between the non-zero digits then are Significant Figure e.g- 40.69 has four Significant Figures.
- If the digits are less than one on the left side of decimal point then zero wouldn’t be counted as Significant Figure, e.g-0.0096 has only two Significant Figures.
- If the digits are greater that are equal to one on the left of decimal than we will count the zero as a Significant Figure, e.g-2.0098 has five Significant Figures.
- Zeros that locates the decimal point in numbers larger than one are not necessarily Significant Figures e.g- 40 has only one Significant Figure, 2000 also has only one Significant Figure.