QUESTION

# Find out the greatest and the smallest 4-digit numbers using any four different digits with conditions as given:Digit 1 is always at thousands’ place.

\begin{align} & \text{Thousands Hundreds Tens Ones} \\ & \text{ 1 9 8 7} \\ \end{align}
\begin{align} & \text{Thousands Hundreds Tens Ones} \\ & \text{ 1 0 2 3} \\ \end{align}