Use the digits $1, 7, 6, 2$ without repetition and make the greatest and smallest four-digit numbers.

Make the greatest and the smallest $4$-digit numbers using any four different digits with digit $4$ is always at tens place.

Greatest   

Smallest

For example, digit $7$ is always at ones place,

Greatest

Smallest

Make the greatest and the smallest $4$-digit numbers using any four different digits with digit $9$ is always at hundreds place.

Greatest   

Smallest

For example, digit $7$ is always at one's place,

Greatest

Smallest

Make the greatest and the smallest $4$-digit numbers using any four different digits with digit $1$ is always at thousands place.

Greatest   

Smallest

For example, digit $7$ is always at ones place,

Greatest

Smallest