significant digit

Từ điển WordNet v3.1 - WordNet Dictionary

noun

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)
- he calculated the answer to four significant figures
• Syn:
significant figure
• Hypernyms:
digit, figure