In positional notation, significant figures (also known as significant digits, precision, or resolution) are digits in a number that is both dependable and absolutely essential for indicating the quantity of something. If a number describing the outcome of measurement (e.g., length, pressure, volume, or mass) includes more digits than the measurement resolution allows, only those digits are trustworthy, and only those can be significant figures.

Addition, subtraction, multiplication, and division of significant digits. Enter numbers, exponential or electronic, and select an operator. When using the calculator, if you do all the log calculations without storing the intermediate results, you will not determine if an error was made. Even if you realize that an error has occurred, you will not determine where the error occurred. For long calculation with mixed operations, enter as many digits as possible in the entire calculation set, and then round the final result accordingly.

Because only reliable digits can be significant, identifying the significant figures in a number requires knowing which digits are reliable (e.g., by knowing the measurement or reporting resolution with which the number is obtained or processed). For example, 3 and 4 in 0.00234 g are not significant if the measurable smallest weight is 0.001 g.

- The presence of non-zero digits inside a measurement or reporting resolution is crucial.
- Significant zeros occur between two significant non-zero digits (significant trapped zeros).
- Leading zeros (zeros to the left of the first non-zero digit) have no meaning. If they are within the measurement or reporting resolution, zeros to the right of the final nonzero digit (trailing zeros) in a number with the decimal point are important.
- Depending on the measurement or reporting resolution, trailing zeros in an integer may or may not be significant.
- There are an endless amount of significant figures in an exact integer.
- The known digits of a mathematical or physical constant have significant figures.

To get to a meaningful number, round up: If you're rounding to one significant figure, look at the first non-zero digit. Examine the digit following the first non-zero digit. if two significant figures are used. After the necessary place value digit, draw a vertical line. If the preceding digit is 5 or more, raise it by one, if it is 4 or less, keep it the same, and fill any spaces to the right of the line with zeros, finishing at the decimal point if there is one.

The number of digits in a figure that expresses a measurement's accuracy rather than its size. The simplest way to figure out how many significant digits a number has is to first see if it has a decimal point. The Atlantic-Pacific Regulation is the name for this rule. The rule specifies that if there is no decimal point, the zeroes on the Atlantic/right side are meaningless. The zeroes on the Pacific/left side are meaningless if a decimal point is present.

All non-zero numerals have meaning. With two exceptions: zeros before the decimal point and zeros after the decimal point. Following the decimal point and before the first nonzero digit are zeros. In quantities higher than one, terminal zeros preceding the decimal point are an unclear circumstance.