Simplify :

555 - 55.5 - 5.555

Given expression:

= 555 - 55.5 - 5.555
= 555.000 - 55.500 - 5.555 $\quad$ [Converting into like decimals]
= 555.000 - (55.500 + 5.555) $\quad$ [Rearranging terms]
= 555.000 - 61.055
= 493.945

$\begin{array}{r|r} 55.500 & 555.000 \ +\phantom{0}5.555 & -\phantom{0}61.055 \ \hline 61.055 & 493.945 \ \hline \end{array}$

Hence, the answer is 493.945