Question

Form the greatest and smallest 4-digit numbers using any one of the given digits twice:

$1,8,0$

Answer 1

Step 1: Use the largest value digit twice and arrange the digits in descending order for the largest number.

$8>1>0$
The required greatest number is 8810.
Step 2: Use the smallest value digit twice and arrange the digits in ascending order for the smallest number

$0<1<8$
Since the smallest value digit is zero, place them in the second leftmost position.
Thus, the required smallest number is 1008.