How many $5-$digit numbers can be formed using $\left(0-9\right)$?

Finding possible $5$ digit numbers formed by $(0-9)$:

The number has $5$ digits. Any digit can be used in the fifth position to create a five-digit number, with the exception of $0$, which will result in a four-digit number.

Therefore, there are $9$ possible options to occupy the fifth position.

Any digit from $0$ to $9$ can be used for the fourth position. That also applies to the third, second, and first places.

In the end, multiply them to arrive at a response:

$9\times 10\times 10\times 10\times 10\Rightarrow 90000$.

Hence, $90000$ numbers can be formed using $\left(0-9\right)$.