The number $100\times b + 10\times c + a$ in the usual form is:

The usual form of $100\times b + 10\times c + a$ is $\mathit{b}\mathit{c}\mathit{a}$.

$100\times b + 10\times c + a = bca$

Where $b$ is in the hundred's place, $c$ is in the tens place, and $a$ is in the one's place.

Therefore, the usual form of $100\times b + 10\times c + a$ is $\mathit{b}\mathit{c}\mathit{a}$.