When there are trailing zeros in a whole number, the number of significant figures is ambiguous. The given number would ordinarily be considered to have 2 significant figures, as the trailing zero would not count. In order to unambiguously specify the significant figures when there are trailing zeros, the number must be written as a decimal fraction or using scientific notation.
Here, we have 610 mK/s = 0.610 K/s = 610 μK/ms. The latter number can only be shown as having 3 significant digits if it is written in scientific notation:
