noun · the remaining unpaid portion of an account or the small change left over from a sum of money

他已经付了大半货款，还剩下一笔尾数。

noun · the fractional part of a number following the decimal point, or the mantissa of a common logarithm

计算时，请务必保留三位尾数。

noun · the minor or insignificant digits of a number that are discarded or adjusted during rounding

四舍五入时，不满五的尾数都要舍掉。