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Calculating the number of significant figures in a number is a relatively simple process, but it depends on a clear understanding of four main rules. The examples below set out the guidance for each rule and provide various examples to help you understand how the calculation is being made in each case.
Significant figures (or significant digits) are the number of digits important to determine the accuracy and precision of measurement, such as length, mass, or volume. Significant digits in math convey the value of a number with accuracy.
For multiplication or division, the rule is to count the number of significant figures in each number being multiplied or divided and then limit the significant figures in the answer to the lowest count. An example is as follows: The final answer, limited to four significant figures, is 4,094.
The significant figures of a given number are those significant or important digits, which convey the meaning according to its accuracy. For example, 6.658 has four significant digits. These substantial figures provide precision to the numbers.
Determine the appropriate number of significant figures in both addition and subtraction, as well as multiplication and division calculations. Calculate the percent uncertainty of a measurement.
Rules for deciding the number of significant figures in a measured quantity: All nonzero digits are significant: 1.234 g has 4 significant figures, 1.2 g has 2 significant figures. Zeroes between nonzero digits are significant: 1002 kg has 4 significant figures, 3.07 mL has 3 significant figures.
Identifying the significant figures in a number requires knowing which digits are meaningful, which requires knowing the resolution with which the number is measured, obtained, or processed.
