Precision refers to the closeness of a set of values obtained for identical measurement of a quantity. Precision depends on the limitations of measuring devices and the skills with which it is used. However, accuracy refers to the closeness of a single measurement to its true value. The digits in a properly measurement are known as significant figures. these are meaningful digits in a measured or calculated quantity. The greater the number of significant figures in a reported result, smaller is the uncertainly and greater is the precision. the zeros at the beginning are not counted. the zeros to the right of a decimal point are counted. in the numbers that do not contain a decimal point. "trailing" zeros may or may not be significant . the purpose of zeros at the end of anumber is to convey the correct range of uncertainly. In the number 2.4560, there are 5 significant digits. which one is the least significant digit?