significant figure

详细解释:【计】 有效位, 有效数位, 有数字
【化】 有效数字

英语解释：

名词 significant figure:

any digit of a number that is known with certainty; any digit of a number beginning with the leftmost non-zero digit and ending with the rightmost non-zero digit (or a zero considered to be the exact value)同义词：significant digit