Question

Using the given digits without repetition form the smallest and the greatest $4-\mathrm{digit}$ numbers.

$6,9,2,4$

Answer 1

Step I: Forming the smallest $4-\mathrm{digit}$ number.

The digits $6,9,2,4$ if written in the increasing order will give the smallest $4-\mathrm{digit}$ number.

The increasing order is $2,4,6,9$.

Therefore, the smallest $4-\mathrm{digit}$ number is $2469$.

Step II: Forming the greatest $4-\mathrm{digit}$ number.

The digits $6,9,2,4$ if written in the decreasing order will give the greatest $4-\mathrm{digit}$ number.

The decreasing order is $9,6,4,2$..

Therefore, the greatest $4-\mathrm{digit}$ number is $9642$.

Hence, the smallest $4-\mathrm{digit}$ number is $2469$ and the greatest $4-\mathrm{digit}$ number is $9642$.