Simplify :

1 - 10.5 + 12.213

Given expression:

= 1 - 10.5 + 12.213
= 1.000 - 10.500 + 12.213 $\quad$ [Converting into like decimals]
= (1.000 + 12.213) - 10.500 $\quad$ [Rearranging terms]
= 13.213 - 10.500
= 2.713

$\begin{array}{r|r} 1.000 & 13.213 \ +\phantom{0}12.213 & -\phantom{0}10.500 \ \hline 13.213 & 2.713 \ \hline \end{array}$

Hence, the answer is 2.713