accuracy

In mathematics, a measure of the precision of a number. The degree of accuracy depends on how many figures or decimal places are used in rounding off the number. For example, the result of a calculation or measurement (such as 13.429314) might be rounded off to three decimal places (13.429), to two decimal places (13.43), to one decimal place (13.4), or to the nearest whole number (13). The first answer is more accurate than the second, the second more accurate than the third, and so on.

Accuracy also refers to a range of errors. For example, an accuracy of ± 5% means that a value may lie between 95% and 105% of a given answer.

Alternatively, a result might be presented to a certain number of significant figures (digits that are important because of their place value). For example, the number 409,318 might be expressed to an accuracy of four significant figures (409,300), three significant figures (409,000), two significant figures (410,000), or one significant figure (400,000). Here again, the first answer is more accurate than the second, and so on.