### Exercise condition:

5
1. Use the digits 4, 7, 1 to form the three-digit number.

The greatest three digit number formed $$=$$ .

The smallest three digit number formed $$=$$ .

2. Use the digits 7, 1, 4 to form four-digit number by taking any one digit twice.

The greatest four digit number formed $$=$$ .

The smallest four digit number formed $$=$$ .