通常我们认为,用“有效数字的最后一位是误差所在的一位”来定义有效数字较为妥当,这里的误差是指偶然误差,或者包括未定的系统误差。对于直接测量的物理量,用“测量结果可靠的位数加上一位可疑数字都是有效数字”来表述这种表述与前面表述是一致的,可以理解为可疑的一位就是存在误差的一位,但是用“测量结果准确的位数加上估计的一位都是有效数字”来表述有效数字,在某些情况下 Generally, we think it is more appropriate to define a significant figure by using “where the last digit of the significant digit is the one where the error is located,” where the error is either accidental error or includes undetermined systematic error. For direct measurement of physical quantities, it is consistent with the previous statement that “the number of reliable digits of a measurement plus a suspicious number is a valid number.” It can be understood that the suspicious one is that there is an error One, but with “the exact number of digits of the measurement plus one of the estimated significant digits” to represent the significant digits, in some cases